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Easy Problem Index

This index is generated by scripts/generate_difficulty_readmes.py from dataset/merged_problems.json.

Problem count: 763

ID Problem Topics
0001 Two Sum Array, Hash Table
0009 Palindrome Number Math
0013 Roman to Integer Hash Table, Math, String
0014 Longest Common Prefix Array, String, Trie
0020 Valid Parentheses String, Stack
0021 Merge Two Sorted Lists Linked List, Recursion
0026 Remove Duplicates from Sorted Array Array, Two Pointers
0027 Remove Element Array, Two Pointers
0028 Find the Index of the First Occurrence in a String Two Pointers, String, String Matching
0035 Search Insert Position Array, Binary Search
0058 Length of Last Word String
0066 Plus One Array, Math
0067 Add Binary Math, String, Bit Manipulation, Simulation
0069 Sqrt(x) Math, Binary Search
0070 Climbing Stairs Math, Dynamic Programming, Memoization
0083 Remove Duplicates from Sorted List Linked List
0088 Merge Sorted Array Array, Two Pointers, Sorting
0094 Binary Tree Inorder Traversal Stack, Tree, Depth-First Search, Binary Tree
0100 Same Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0101 Symmetric Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0104 Maximum Depth of Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0108 Convert Sorted Array to Binary Search Tree Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree
0110 Balanced Binary Tree Tree, Depth-First Search, Binary Tree
0111 Minimum Depth of Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0112 Path Sum Tree, Depth-First Search, Breadth-First Search, Binary Tree
0118 Pascal's Triangle Array, Dynamic Programming
0119 Pascal's Triangle II Array, Dynamic Programming
0121 Best Time to Buy and Sell Stock Array, Dynamic Programming
0125 Valid Palindrome Two Pointers, String
0136 Single Number Array, Bit Manipulation
0141 Linked List Cycle Hash Table, Linked List, Two Pointers
0144 Binary Tree Preorder Traversal Stack, Tree, Depth-First Search, Binary Tree
0145 Binary Tree Postorder Traversal Stack, Tree, Depth-First Search, Binary Tree
0160 Intersection of Two Linked Lists Hash Table, Linked List, Two Pointers
0168 Excel Sheet Column Title Math, String
0169 Majority Element Array, Hash Table, Divide and Conquer, Sorting, Counting
0171 Excel Sheet Column Number Math, String
0175 Combine Two Tables Database
0181 Employees Earning More Than Their Managers Database
0182 Duplicate Emails Database
0183 Customers Who Never Order Database
0190 Reverse Bits Divide and Conquer, Bit Manipulation
0191 Number of 1 Bits Divide and Conquer, Bit Manipulation
0193 Valid Phone Numbers Shell
0195 Tenth Line Shell
0196 Delete Duplicate Emails Database
0197 Rising Temperature Database
0202 Happy Number Hash Table, Math, Two Pointers
0203 Remove Linked List Elements Linked List, Recursion
0205 Isomorphic Strings Hash Table, String
0206 Reverse Linked List Linked List, Recursion
0217 Contains Duplicate Array, Hash Table, Sorting
0219 Contains Duplicate II Array, Hash Table, Sliding Window
0222 Count Complete Tree Nodes Binary Search, Bit Manipulation, Tree, Binary Tree
0225 Implement Stack using Queues Stack, Design, Queue
0226 Invert Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0228 Summary Ranges Array
0231 Power of Two Math, Bit Manipulation, Recursion
0232 Implement Queue using Stacks Stack, Design, Queue
0234 Palindrome Linked List Linked List, Two Pointers, Stack, Recursion
0242 Valid Anagram Hash Table, String, Sorting
0257 Binary Tree Paths String, Backtracking, Tree, Depth-First Search, Binary Tree
0258 Add Digits Math, Simulation, Number Theory
0263 Ugly Number Math
0268 Missing Number Array, Hash Table, Math, Binary Search, Bit Manipulation, Sorting
0278 First Bad Version Binary Search, Interactive
0283 Move Zeroes Array, Two Pointers
0290 Word Pattern Hash Table, String
0292 Nim Game Math, Brainteaser, Game Theory
0303 Range Sum Query - Immutable Array, Design, Prefix Sum
0326 Power of Three Math, Recursion
0338 Counting Bits Dynamic Programming, Bit Manipulation
0342 Power of Four Math, Bit Manipulation, Recursion
0344 Reverse String Two Pointers, String
0345 Reverse Vowels of a String Two Pointers, String
0349 Intersection of Two Arrays Array, Hash Table, Two Pointers, Binary Search, Sorting
0350 Intersection of Two Arrays II Array, Hash Table, Two Pointers, Binary Search, Sorting
0367 Valid Perfect Square Math, Binary Search
0374 Guess Number Higher or Lower Binary Search, Interactive
0383 Ransom Note Hash Table, String, Counting
0387 First Unique Character in a String Hash Table, String, Queue, Counting
0389 Find the Difference Hash Table, String, Bit Manipulation, Sorting
0392 Is Subsequence Two Pointers, String, Dynamic Programming
0401 Binary Watch Backtracking, Bit Manipulation
0404 Sum of Left Leaves Tree, Depth-First Search, Breadth-First Search, Binary Tree
0405 Convert a Number to Hexadecimal Math, String, Bit Manipulation
0409 Longest Palindrome Hash Table, String, Greedy
0412 Fizz Buzz Math, String, Simulation
0414 Third Maximum Number Array, Sorting
0415 Add Strings Math, String, Simulation
0434 Number of Segments in a String String
0441 Arranging Coins Math, Binary Search
0448 Find All Numbers Disappeared in an Array Array, Hash Table
0455 Assign Cookies Array, Two Pointers, Greedy, Sorting
0459 Repeated Substring Pattern String, String Matching
0461 Hamming Distance Bit Manipulation
0463 Island Perimeter Array, Depth-First Search, Breadth-First Search, Matrix
0476 Number Complement Bit Manipulation
0482 License Key Formatting String
0485 Max Consecutive Ones Array
0492 Construct the Rectangle Math
0495 Teemo Attacking Array, Simulation
0496 Next Greater Element I Array, Hash Table, Stack, Monotonic Stack
0500 Keyboard Row Array, Hash Table, String
0501 Find Mode in Binary Search Tree Tree, Depth-First Search, Binary Search Tree, Binary Tree
0504 Base 7 Math, String
0506 Relative Ranks Array, Sorting, Heap (Priority Queue)
0507 Perfect Number Math
0509 Fibonacci Number Math, Dynamic Programming, Recursion, Memoization
0511 Game Play Analysis I Database
0520 Detect Capital String
0521 Longest Uncommon Subsequence I String
0530 Minimum Absolute Difference in BST Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree
0541 Reverse String II Two Pointers, String
0543 Diameter of Binary Tree Tree, Depth-First Search, Binary Tree
0551 Student Attendance Record I String
0557 Reverse Words in a String III Two Pointers, String
0559 Maximum Depth of N-ary Tree Tree, Depth-First Search, Breadth-First Search
0561 Array Partition Array, Greedy, Sorting, Counting Sort
0563 Binary Tree Tilt Tree, Depth-First Search, Binary Tree
0566 Reshape the Matrix Array, Matrix, Simulation
0572 Subtree of Another Tree Tree, Depth-First Search, String Matching, Binary Tree, Hash Function
0575 Distribute Candies Array, Hash Table
0577 Employee Bonus Database
0584 Find Customer Referee Database
0586 Customer Placing the Largest Number of Orders Database
0589 N-ary Tree Preorder Traversal Stack, Tree, Depth-First Search
0590 N-ary Tree Postorder Traversal Stack, Tree, Depth-First Search
0594 Longest Harmonious Subsequence Array, Hash Table, Sliding Window, Sorting, Counting
0595 Big Countries Database
0596 Classes With at Least 5 Students Database
0598 Range Addition II Array, Math
0599 Minimum Index Sum of Two Lists Array, Hash Table, String
0605 Can Place Flowers Array, Greedy
0607 Sales Person Database
0610 Triangle Judgement Database
0617 Merge Two Binary Trees Tree, Depth-First Search, Breadth-First Search, Binary Tree
0619 Biggest Single Number Database
0620 Not Boring Movies Database
0627 Swap Salary Database
0628 Maximum Product of Three Numbers Array, Math, Sorting
0637 Average of Levels in Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0643 Maximum Average Subarray I Array, Sliding Window
0645 Set Mismatch Array, Hash Table, Bit Manipulation, Sorting
0653 Two Sum IV - Input is a BST Hash Table, Two Pointers, Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree
0657 Robot Return to Origin String, Simulation
0661 Image Smoother Array, Matrix
0671 Second Minimum Node In a Binary Tree Tree, Depth-First Search, Binary Tree
0674 Longest Continuous Increasing Subsequence Array
0680 Valid Palindrome II Two Pointers, String, Greedy
0682 Baseball Game Array, Stack, Simulation
0693 Binary Number with Alternating Bits Bit Manipulation
0696 Count Binary Substrings Two Pointers, String
0697 Degree of an Array Array, Hash Table
0700 Search in a Binary Search Tree Tree, Binary Search Tree, Binary Tree
0703 Kth Largest Element in a Stream Tree, Design, Binary Search Tree, Heap (Priority Queue), Binary Tree, Data Stream
0704 Binary Search Array, Binary Search
0705 Design HashSet Array, Hash Table, Linked List, Design, Hash Function
0706 Design HashMap Array, Hash Table, Linked List, Design, Hash Function
0709 To Lower Case String
0717 1-bit and 2-bit Characters Array
0724 Find Pivot Index Array, Prefix Sum
0728 Self Dividing Numbers Math
0733 Flood Fill Array, Depth-First Search, Breadth-First Search, Matrix
0744 Find Smallest Letter Greater Than Target Array, Binary Search
0746 Min Cost Climbing Stairs Array, Dynamic Programming
0747 Largest Number At Least Twice of Others Array, Sorting
0748 Shortest Completing Word Array, Hash Table, String
0762 Prime Number of Set Bits in Binary Representation Math, Bit Manipulation
0766 Toeplitz Matrix Array, Matrix
0771 Jewels and Stones Hash Table, String
0783 Minimum Distance Between BST Nodes Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree
0796 Rotate String String, String Matching
0804 Unique Morse Code Words Array, Hash Table, String
0806 Number of Lines To Write String Array, String
0812 Largest Triangle Area Array, Math, Geometry
0819 Most Common Word Array, Hash Table, String, Counting
0821 Shortest Distance to a Character Array, Two Pointers, String
0824 Goat Latin String
0830 Positions of Large Groups String
0832 Flipping an Image Array, Two Pointers, Bit Manipulation, Matrix, Simulation
0836 Rectangle Overlap Math, Geometry
0844 Backspace String Compare Two Pointers, String, Stack, Simulation
0859 Buddy Strings Hash Table, String
0860 Lemonade Change Array, Greedy
0867 Transpose Matrix Array, Matrix, Simulation
0868 Binary Gap Bit Manipulation
0872 Leaf-Similar Trees Tree, Depth-First Search, Binary Tree
0876 Middle of the Linked List Linked List, Two Pointers
0883 Projection Area of 3D Shapes Array, Math, Geometry, Matrix
0884 Uncommon Words from Two Sentences Hash Table, String, Counting
0888 Fair Candy Swap Array, Hash Table, Binary Search, Sorting
0892 Surface Area of 3D Shapes Array, Math, Geometry, Matrix
0896 Monotonic Array Array
0897 Increasing Order Search Tree Stack, Tree, Depth-First Search, Binary Search Tree, Binary Tree
0905 Sort Array By Parity Array, Two Pointers, Sorting
0908 Smallest Range I Array, Math
0914 X of a Kind in a Deck of Cards Array, Hash Table, Math, Counting, Number Theory
0917 Reverse Only Letters Two Pointers, String
0922 Sort Array By Parity II Array, Two Pointers, Sorting
0925 Long Pressed Name Two Pointers, String
0929 Unique Email Addresses Array, Hash Table, String
0933 Number of Recent Calls Design, Queue, Data Stream
0938 Range Sum of BST Tree, Depth-First Search, Binary Search Tree, Binary Tree
0941 Valid Mountain Array Array
0942 DI String Match Array, Two Pointers, String, Greedy
0944 Delete Columns to Make Sorted Array, String
0953 Verifying an Alien Dictionary Array, Hash Table, String
0961 N-Repeated Element in Size 2N Array Array, Hash Table
0965 Univalued Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0976 Largest Perimeter Triangle Array, Math, Greedy, Sorting
0977 Squares of a Sorted Array Array, Two Pointers, Sorting
0989 Add to Array-Form of Integer Array, Math
0993 Cousins in Binary Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
0997 Find the Town Judge Array, Hash Table, Graph
0999 Available Captures for Rook Array, Matrix, Simulation
1002 Find Common Characters Array, Hash Table, String
1005 Maximize Sum Of Array After K Negations Array, Greedy, Sorting
1009 Complement of Base 10 Integer Bit Manipulation
1013 Partition Array Into Three Parts With Equal Sum Array, Greedy
1018 Binary Prefix Divisible By 5 Array, Bit Manipulation
1021 Remove Outermost Parentheses String, Stack
1022 Sum of Root To Leaf Binary Numbers Tree, Depth-First Search, Binary Tree
1025 Divisor Game Math, Dynamic Programming, Brainteaser, Game Theory
1030 Matrix Cells in Distance Order Array, Math, Geometry, Sorting, Matrix
1037 Valid Boomerang Array, Math, Geometry
1046 Last Stone Weight Array, Heap (Priority Queue)
1047 Remove All Adjacent Duplicates In String String, Stack
1050 Actors and Directors Who Cooperated At Least Three Times Database
1051 Height Checker Array, Sorting, Counting Sort
1068 Product Sales Analysis I Database
1071 Greatest Common Divisor of Strings Math, String
1075 Project Employees I Database
1078 Occurrences After Bigram String
1084 Sales Analysis III Database
1089 Duplicate Zeros Array, Two Pointers
1103 Distribute Candies to People Math, Simulation
1108 Defanging an IP Address String
1114 Print in Order Concurrency
1122 Relative Sort Array Array, Hash Table, Sorting, Counting Sort
1128 Number of Equivalent Domino Pairs Array, Hash Table, Counting
1137 N-th Tribonacci Number Math, Dynamic Programming, Memoization
1141 User Activity for the Past 30 Days I Database
1148 Article Views I Database
1154 Day of the Year Math, String
1160 Find Words That Can Be Formed by Characters Array, Hash Table, String, Counting
1175 Prime Arrangements Math
1179 Reformat Department Table Database
1184 Distance Between Bus Stops Array
1185 Day of the Week Math
1189 Maximum Number of Balloons Hash Table, String, Counting
1200 Minimum Absolute Difference Array, Sorting
1207 Unique Number of Occurrences Array, Hash Table
1211 Queries Quality and Percentage Database
1217 Minimum Cost to Move Chips to The Same Position Array, Math, Greedy
1221 Split a String in Balanced Strings String, Greedy, Counting
1232 Check If It Is a Straight Line Array, Math, Geometry
1251 Average Selling Price Database
1252 Cells with Odd Values in a Matrix Array, Math, Simulation
1260 Shift 2D Grid Array, Matrix, Simulation
1266 Minimum Time Visiting All Points Array, Math, Geometry
1275 Find Winner on a Tic Tac Toe Game Array, Hash Table, Matrix, Simulation
1280 Students and Examinations Database
1281 Subtract the Product and Sum of Digits of an Integer Math
1287 Element Appearing More Than 25% In Sorted Array Array
1290 Convert Binary Number in a Linked List to Integer Linked List, Math
1295 Find Numbers with Even Number of Digits Array, Math
1299 Replace Elements with Greatest Element on Right Side Array
1304 Find N Unique Integers Sum up to Zero Array, Math
1309 Decrypt String from Alphabet to Integer Mapping String
1313 Decompress Run-Length Encoded List Array
1317 Convert Integer to the Sum of Two No-Zero Integers Math
1323 Maximum 69 Number Math, Greedy
1327 List the Products Ordered in a Period Database
1331 Rank Transform of an Array Array, Hash Table, Sorting
1332 Remove Palindromic Subsequences Two Pointers, String
1337 The K Weakest Rows in a Matrix Array, Binary Search, Sorting, Heap (Priority Queue), Matrix
1342 Number of Steps to Reduce a Number to Zero Math, Bit Manipulation
1346 Check If N and Its Double Exist Array, Hash Table, Two Pointers, Binary Search, Sorting
1351 Count Negative Numbers in a Sorted Matrix Array, Binary Search, Matrix
1356 Sort Integers by The Number of 1 Bits Array, Bit Manipulation, Sorting, Counting
1360 Number of Days Between Two Dates Math, String
1365 How Many Numbers Are Smaller Than the Current Number Array, Hash Table, Sorting, Counting Sort
1370 Increasing Decreasing String Hash Table, String, Counting
1374 Generate a String With Characters That Have Odd Counts String
1378 Replace Employee ID With The Unique Identifier Database
1379 Find a Corresponding Node of a Binary Tree in a Clone of That Tree Tree, Depth-First Search, Breadth-First Search, Binary Tree
1380 Lucky Numbers in a Matrix Array, Matrix
1385 Find the Distance Value Between Two Arrays Array, Two Pointers, Binary Search, Sorting
1389 Create Target Array in the Given Order Array, Simulation
1394 Find Lucky Integer in an Array Array, Hash Table, Counting
1399 Count Largest Group Hash Table, Math
1403 Minimum Subsequence in Non-Increasing Order Array, Greedy, Sorting
1407 Top Travellers Database
1408 String Matching in an Array Array, String, String Matching
1413 Minimum Value to Get Positive Step by Step Sum Array, Prefix Sum
1417 Reformat The String String
1422 Maximum Score After Splitting a String String, Prefix Sum
1431 Kids With the Greatest Number of Candies Array
1436 Destination City Array, Hash Table, String
1437 Check If All 1's Are at Least Length K Places Away Array
1446 Consecutive Characters String
1450 Number of Students Doing Homework at a Given Time Array
1455 Check If a Word Occurs As a Prefix of Any Word in a Sentence Two Pointers, String, String Matching
1460 Make Two Arrays Equal by Reversing Subarrays Array, Hash Table, Sorting
1464 Maximum Product of Two Elements in an Array Array, Sorting, Heap (Priority Queue)
1470 Shuffle the Array Array
1475 Final Prices With a Special Discount in a Shop Array, Stack, Monotonic Stack
1480 Running Sum of 1d Array Array, Prefix Sum
1484 Group Sold Products By The Date Database
1486 XOR Operation in an Array Math, Bit Manipulation
1491 Average Salary Excluding the Minimum and Maximum Salary Array, Sorting
1496 Path Crossing Hash Table, String
1502 Can Make Arithmetic Progression From Sequence Array, Sorting
1507 Reformat Date String
1512 Number of Good Pairs Array, Hash Table, Math, Counting
1517 Find Users With Valid E-Mails Database
1518 Water Bottles Math, Simulation
1523 Count Odd Numbers in an Interval Range Math
1527 Patients With a Condition Database
1528 Shuffle String Array, String
1534 Count Good Triplets Array, Enumeration
1539 Kth Missing Positive Number Array, Binary Search
1544 Make The String Great String, Stack
1550 Three Consecutive Odds Array
1556 Thousand Separator String
1560 Most Visited Sector in a Circular Track Array, Simulation
1566 Detect Pattern of Length M Repeated K or More Times Array, Enumeration
1572 Matrix Diagonal Sum Array, Matrix
1576 Replace All ?'s to Avoid Consecutive Repeating Characters String
1581 Customer Who Visited but Did Not Make Any Transactions Database
1582 Special Positions in a Binary Matrix Array, Matrix
1587 Bank Account Summary II Database
1588 Sum of All Odd Length Subarrays Array, Math, Prefix Sum
1592 Rearrange Spaces Between Words String
1598 Crawler Log Folder Array, String, Stack
1603 Design Parking System Design, Simulation, Counting
1608 Special Array With X Elements Greater Than or Equal X Array, Binary Search, Sorting
1614 Maximum Nesting Depth of the Parentheses String, Stack
1619 Mean of Array After Removing Some Elements Array, Sorting
1624 Largest Substring Between Two Equal Characters Hash Table, String
1629 Slowest Key Array, String
1633 Percentage of Users Attended a Contest Database
1636 Sort Array by Increasing Frequency Array, Hash Table, Sorting
1637 Widest Vertical Area Between Two Points Containing No Points Array, Sorting
1640 Check Array Formation Through Concatenation Array, Hash Table
1646 Get Maximum in Generated Array Array, Simulation
1652 Defuse the Bomb Array, Sliding Window
1656 Design an Ordered Stream Array, Hash Table, Design, Data Stream
1661 Average Time of Process per Machine Database
1662 Check If Two String Arrays are Equivalent Array, String
1667 Fix Names in a Table Database
1668 Maximum Repeating Substring String, Dynamic Programming, String Matching
1672 Richest Customer Wealth Array, Matrix
1678 Goal Parser Interpretation String
1683 Invalid Tweets Database
1684 Count the Number of Consistent Strings Array, Hash Table, String, Bit Manipulation, Counting
1688 Count of Matches in Tournament Math, Simulation
1693 Daily Leads and Partners Database
1694 Reformat Phone Number String
1700 Number of Students Unable to Eat Lunch Array, Stack, Queue, Simulation
1704 Determine if String Halves Are Alike String, Counting
1710 Maximum Units on a Truck Array, Greedy, Sorting
1716 Calculate Money in Leetcode Bank Math
1720 Decode XORed Array Array, Bit Manipulation
1725 Number Of Rectangles That Can Form The Largest Square Array
1729 Find Followers Count Database
1731 The Number of Employees Which Report to Each Employee Database
1732 Find the Highest Altitude Array, Prefix Sum
1736 Latest Time by Replacing Hidden Digits String, Greedy
1741 Find Total Time Spent by Each Employee Database
1742 Maximum Number of Balls in a Box Hash Table, Math, Counting
1748 Sum of Unique Elements Array, Hash Table, Counting
1752 Check if Array Is Sorted and Rotated Array
1757 Recyclable and Low Fat Products Database
1758 Minimum Changes To Make Alternating Binary String String
1763 Longest Nice Substring Hash Table, String, Divide and Conquer, Bit Manipulation, Sliding Window
1768 Merge Strings Alternately Two Pointers, String
1773 Count Items Matching a Rule Array, String
1779 Find Nearest Point That Has the Same X or Y Coordinate Array
1784 Check if Binary String Has at Most One Segment of Ones String
1789 Primary Department for Each Employee Database
1790 Check if One String Swap Can Make Strings Equal Hash Table, String, Counting
1791 Find Center of Star Graph Graph
1795 Rearrange Products Table Database
1796 Second Largest Digit in a String Hash Table, String
1800 Maximum Ascending Subarray Sum Array
1805 Number of Different Integers in a String Hash Table, String
1812 Determine Color of a Chessboard Square Math, String
1816 Truncate Sentence Array, String
1822 Sign of the Product of an Array Array, Math
1827 Minimum Operations to Make the Array Increasing Array, Greedy
1832 Check if the Sentence Is Pangram Hash Table, String
1837 Sum of Digits in Base K Math
1844 Replace All Digits with Characters String
1848 Minimum Distance to the Target Element Array
1854 Maximum Population Year Array, Counting, Prefix Sum
1859 Sorting the Sentence String, Sorting
1863 Sum of All Subset XOR Totals Array, Math, Backtracking, Bit Manipulation, Combinatorics, Enumeration
1869 Longer Contiguous Segments of Ones than Zeros String
1873 Calculate Special Bonus Database
1876 Substrings of Size Three with Distinct Characters Hash Table, String, Sliding Window, Counting
1880 Check if Word Equals Summation of Two Words String
1886 Determine Whether Matrix Can Be Obtained By Rotation Array, Matrix
1890 The Latest Login in 2020 Database
1893 Check if All the Integers in a Range Are Covered Array, Hash Table, Prefix Sum
1897 Redistribute Characters to Make All Strings Equal Hash Table, String, Counting
1903 Largest Odd Number in String Math, String, Greedy
1909 Remove One Element to Make the Array Strictly Increasing Array
1913 Maximum Product Difference Between Two Pairs Array, Sorting
1920 Build Array from Permutation Array, Simulation
1925 Count Square Sum Triples Math, Enumeration
1929 Concatenation of Array Array, Simulation
1935 Maximum Number of Words You Can Type Hash Table, String
1941 Check if All Characters Have Equal Number of Occurrences Hash Table, String, Counting
1945 Sum of Digits of String After Convert String, Simulation
1952 Three Divisors Math, Enumeration, Number Theory
1957 Delete Characters to Make Fancy String String
1961 Check If String Is a Prefix of Array Array, Two Pointers, String
1965 Employees With Missing Information Database
1967 Number of Strings That Appear as Substrings in Word Array, String
1971 Find if Path Exists in Graph Depth-First Search, Breadth-First Search, Union Find, Graph
1974 Minimum Time to Type Word Using Special Typewriter String, Greedy
1978 Employees Whose Manager Left the Company Database
1979 Find Greatest Common Divisor of Array Array, Math, Number Theory
1984 Minimum Difference Between Highest and Lowest of K Scores Array, Sliding Window, Sorting
1991 Find the Middle Index in Array Array, Prefix Sum
1995 Count Special Quadruplets Array, Hash Table, Enumeration
2000 Reverse Prefix of Word Two Pointers, String, Stack
2006 Count Number of Pairs With Absolute Difference K Array, Hash Table, Counting
2011 Final Value of Variable After Performing Operations Array, String, Simulation
2016 Maximum Difference Between Increasing Elements Array
2022 Convert 1D Array Into 2D Array Array, Matrix, Simulation
2027 Minimum Moves to Convert String String, Greedy
2032 Two Out of Three Array, Hash Table, Bit Manipulation
2037 Minimum Number of Moves to Seat Everyone Array, Greedy, Sorting, Counting Sort
2042 Check if Numbers Are Ascending in a Sentence String
2047 Number of Valid Words in a Sentence String
2053 Kth Distinct String in an Array Array, Hash Table, String, Counting
2057 Smallest Index With Equal Value Array
2062 Count Vowel Substrings of a String Hash Table, String
2068 Check Whether Two Strings are Almost Equivalent Hash Table, String, Counting
2073 Time Needed to Buy Tickets Array, Queue, Simulation
2078 Two Furthest Houses With Different Colors Array, Greedy
2085 Count Common Words With One Occurrence Array, Hash Table, String, Counting
2089 Find Target Indices After Sorting Array Array, Binary Search, Sorting
2094 Finding 3-Digit Even Numbers Array, Hash Table, Sorting, Enumeration
2099 Find Subsequence of Length K With the Largest Sum Array, Hash Table, Sorting, Heap (Priority Queue)
2103 Rings and Rods Hash Table, String
2108 Find First Palindromic String in the Array Array, Two Pointers, String
2114 Maximum Number of Words Found in Sentences Array, String
2119 A Number After a Double Reversal Math
2124 Check if All A's Appears Before All B's String
2129 Capitalize the Title String
2133 Check if Every Row and Column Contains All Numbers Array, Hash Table, Matrix
2138 Divide a String Into Groups of Size k String, Simulation
2144 Minimum Cost of Buying Candies With Discount Array, Greedy, Sorting
2148 Count Elements With Strictly Smaller and Greater Elements Array, Sorting, Counting
2154 Keep Multiplying Found Values by Two Array, Hash Table, Sorting, Simulation
2160 Minimum Sum of Four Digit Number After Splitting Digits Math, Greedy, Sorting
2164 Sort Even and Odd Indices Independently Array, Sorting
2169 Count Operations to Obtain Zero Math, Simulation
2176 Count Equal and Divisible Pairs in an Array Array
2180 Count Integers With Even Digit Sum Math, Simulation
2185 Counting Words With a Given Prefix Array, String, String Matching
2190 Most Frequent Number Following Key In an Array Array, Hash Table, Counting
2194 Cells in a Range on an Excel Sheet String
2200 Find All K-Distant Indices in an Array Array, Two Pointers
2206 Divide Array Into Equal Pairs Array, Hash Table, Bit Manipulation, Counting
2210 Count Hills and Valleys in an Array Array
2215 Find the Difference of Two Arrays Array, Hash Table
2220 Minimum Bit Flips to Convert Number Bit Manipulation
2224 Minimum Number of Operations to Convert Time String, Greedy
2231 Largest Number After Digit Swaps by Parity Sorting, Heap (Priority Queue)
2235 Add Two Integers Math
2236 Root Equals Sum of Children Tree, Binary Tree
2239 Find Closest Number to Zero Array
2243 Calculate Digit Sum of a String String, Simulation
2248 Intersection of Multiple Arrays Array, Hash Table, Sorting, Counting
2255 Count Prefixes of a Given String Array, String
2259 Remove Digit From Number to Maximize Result String, Greedy, Enumeration
2264 Largest 3-Same-Digit Number in String String
2269 Find the K-Beauty of a Number Math, String, Sliding Window
2273 Find Resultant Array After Removing Anagrams Array, Hash Table, String, Sorting
2278 Percentage of Letter in String String
2283 Check if Number Has Equal Digit Count and Digit Value Hash Table, String, Counting
2287 Rearrange Characters to Make Target String Hash Table, String, Counting
2293 Min Max Game Array, Simulation
2299 Strong Password Checker II String
2303 Calculate Amount Paid in Taxes Array, Simulation
2309 Greatest English Letter in Upper and Lower Case Hash Table, String, Enumeration
2315 Count Asterisks String
2319 Check if Matrix Is X-Matrix Array, Matrix
2325 Decode the Message Hash Table, String
2331 Evaluate Boolean Binary Tree Tree, Depth-First Search, Binary Tree
2335 Minimum Amount of Time to Fill Cups Array, Greedy, Sorting, Heap (Priority Queue)
2341 Maximum Number of Pairs in Array Array, Hash Table, Counting
2347 Best Poker Hand Array, Hash Table, Counting
2351 First Letter to Appear Twice Hash Table, String, Bit Manipulation, Counting
2356 Number of Unique Subjects Taught by Each Teacher Database
2357 Make Array Zero by Subtracting Equal Amounts Array, Hash Table, Greedy, Sorting, Heap (Priority Queue), Simulation
2363 Merge Similar Items Array, Hash Table, Sorting, Ordered Set
2367 Number of Arithmetic Triplets Array, Hash Table, Two Pointers, Enumeration
2373 Largest Local Values in a Matrix Array, Matrix
2379 Minimum Recolors to Get K Consecutive Black Blocks String, Sliding Window
2383 Minimum Hours of Training to Win a Competition Array, Greedy
2389 Longest Subsequence With Limited Sum Array, Binary Search, Greedy, Sorting, Prefix Sum
2395 Find Subarrays With Equal Sum Array, Hash Table
2399 Check Distances Between Same Letters Array, Hash Table, String
2404 Most Frequent Even Element Array, Hash Table, Counting
2409 Count Days Spent Together Math, String
2413 Smallest Even Multiple Math, Number Theory
2418 Sort the People Array, Hash Table, String, Sorting
2423 Remove Letter To Equalize Frequency Hash Table, String, Counting
2427 Number of Common Factors Math, Enumeration, Number Theory
2432 The Employee That Worked on the Longest Task Array
2437 Number of Valid Clock Times String, Enumeration
2441 Largest Positive Integer That Exists With Its Negative Array, Hash Table, Two Pointers, Sorting
2446 Determine if Two Events Have Conflict Array, String
2451 Odd String Difference Array, Hash Table, String
2455 Average Value of Even Numbers That Are Divisible by Three Array, Math
2460 Apply Operations to an Array Array, Two Pointers, Simulation
2465 Number of Distinct Averages Array, Hash Table, Two Pointers, Sorting
2469 Convert the Temperature Math
2475 Number of Unequal Triplets in Array Array, Hash Table, Sorting
2481 Minimum Cuts to Divide a Circle Math, Geometry
2485 Find the Pivot Integer Math, Prefix Sum
2490 Circular Sentence String
2496 Maximum Value of a String in an Array Array, String
2500 Delete Greatest Value in Each Row Array, Sorting, Heap (Priority Queue), Matrix, Simulation
2506 Count Pairs Of Similar Strings Array, Hash Table, String, Bit Manipulation, Counting
2511 Maximum Enemy Forts That Can Be Captured Array, Two Pointers
2515 Shortest Distance to Target String in a Circular Array Array, String
2520 Count the Digits That Divide a Number Math
2525 Categorize Box According to Criteria Math
2529 Maximum Count of Positive Integer and Negative Integer Array, Binary Search, Counting
2535 Difference Between Element Sum and Digit Sum of an Array Array, Math
2540 Minimum Common Value Array, Hash Table, Two Pointers, Binary Search
2544 Alternating Digit Sum Math
2549 Count Distinct Numbers on Board Array, Hash Table, Math, Simulation
2553 Separate the Digits in an Array Array, Simulation
2558 Take Gifts From the Richest Pile Array, Heap (Priority Queue), Simulation
2562 Find the Array Concatenation Value Array, Two Pointers, Simulation
2566 Maximum Difference by Remapping a Digit Math, Greedy
2570 Merge Two 2D Arrays by Summing Values Array, Hash Table, Two Pointers
2574 Left and Right Sum Differences Array, Prefix Sum
2578 Split With Minimum Sum Math, Greedy, Sorting
2582 Pass the Pillow Math, Simulation
2586 Count the Number of Vowel Strings in Range Array, String, Counting
2591 Distribute Money to Maximum Children Math, Greedy
2595 Number of Even and Odd Bits Bit Manipulation
2600 K Items With the Maximum Sum Math, Greedy
2605 Form Smallest Number From Two Digit Arrays Array, Hash Table, Enumeration
2609 Find the Longest Balanced Substring of a Binary String String
2614 Prime In Diagonal Array, Math, Matrix, Number Theory
2619 Array Prototype Last -
2620 Counter -
2621 Sleep -
2626 Array Reduce Transformation -
2629 Function Composition -
2634 Filter Elements from Array -
2635 Apply Transform Over Each Element in Array -
2639 Find the Width of Columns of a Grid Array, Matrix
2643 Row With Maximum Ones Array, Matrix
2644 Find the Maximum Divisibility Score Array
2648 Generate Fibonacci Sequence -
2651 Calculate Delayed Arrival Time Math
2652 Sum Multiples Math
2656 Maximum Sum With Exactly K Elements Array, Greedy
2660 Determine the Winner of a Bowling Game Array, Simulation
2665 Counter II -
2666 Allow One Function Call -
2667 Create Hello World Function -
2670 Find the Distinct Difference Array Array, Hash Table
2677 Chunk Array -
2678 Number of Senior Citizens Array, String
2682 Find the Losers of the Circular Game Array, Hash Table, Simulation
2695 Array Wrapper -
2696 Minimum String Length After Removing Substrings String, Stack, Simulation
2697 Lexicographically Smallest Palindrome Two Pointers, String, Greedy
2703 Return Length of Arguments Passed -
2704 To Be Or Not To Be -
2706 Buy Two Chocolates Array, Greedy, Sorting
2710 Remove Trailing Zeros From a String String
2715 Timeout Cancellation -
2716 Minimize String Length Hash Table, String
2717 Semi-Ordered Permutation Array, Simulation
2723 Add Two Promises -
2724 Sort By -
2725 Interval Cancellation -
2726 Calculator with Method Chaining -
2727 Is Object Empty -
2729 Check if The Number is Fascinating Hash Table, Math
2733 Neither Minimum nor Maximum Array, Sorting
2739 Total Distance Traveled Math, Simulation
2744 Find Maximum Number of String Pairs Array, Hash Table, String, Simulation
2748 Number of Beautiful Pairs Array, Hash Table, Math, Counting, Number Theory
2760 Longest Even Odd Subarray With Threshold Array, Sliding Window
2765 Longest Alternating Subarray Array, Enumeration
2769 Find the Maximum Achievable Number Math
2778 Sum of Squares of Special Elements Array, Enumeration
2784 Check if Array is Good Array, Hash Table, Sorting
2788 Split Strings by Separator Array, String
2798 Number of Employees Who Met the Target Array
2806 Account Balance After Rounded Purchase Math
2810 Faulty Keyboard String, Simulation
2815 Max Pair Sum in an Array Array, Hash Table
2824 Count Pairs Whose Sum is Less than Target Array, Two Pointers, Binary Search, Sorting
2828 Check if a String Is an Acronym of Words Array, String
2833 Furthest Point From Origin String, Counting
2839 Check if Strings Can be Made Equal With Operations I String
2843 Count Symmetric Integers Math, Enumeration
2848 Points That Intersect With Cars Array, Hash Table, Prefix Sum
2855 Minimum Right Shifts to Sort the Array Array
2859 Sum of Values at Indices With K Set Bits Array, Bit Manipulation
2864 Maximum Odd Binary Number Math, String, Greedy
2869 Minimum Operations to Collect Elements Array, Hash Table, Bit Manipulation
2873 Maximum Value of an Ordered Triplet I Array
2877 Create a DataFrame from List -
2878 Get the Size of a DataFrame -
2879 Display the First Three Rows -
2880 Select Data -
2881 Create a New Column -
2882 Drop Duplicate Rows -
2883 Drop Missing Data -
2884 Modify Columns -
2885 Rename Columns -
2886 Change Data Type -
2887 Fill Missing Data -
2888 Reshape Data: Concatenate -
2889 Reshape Data: Pivot -
2890 Reshape Data: Melt -
2891 Method Chaining -
2894 Divisible and Non-divisible Sums Difference Math
2899 Last Visited Integers Array, Simulation
2900 Longest Unequal Adjacent Groups Subsequence I Array, String, Dynamic Programming, Greedy
2903 Find Indices With Index and Value Difference I Array, Two Pointers
2908 Minimum Sum of Mountain Triplets I Array
2913 Subarrays Distinct Element Sum of Squares I Array, Hash Table
2917 Find the K-or of an Array Array, Bit Manipulation
2923 Find Champion I Array, Matrix
2928 Distribute Candies Among Children I Math, Combinatorics, Enumeration
2932 Maximum Strong Pair XOR I Array, Hash Table, Bit Manipulation, Trie, Sliding Window
2937 Make Three Strings Equal String
2942 Find Words Containing Character Array, String
2946 Matrix Similarity After Cyclic Shifts Array, Math, Matrix, Simulation
2951 Find the Peaks Array, Enumeration
2956 Find Common Elements Between Two Arrays Array, Hash Table
2960 Count Tested Devices After Test Operations Array, Simulation, Counting
2965 Find Missing and Repeated Values Array, Hash Table, Math, Matrix
2970 Count the Number of Incremovable Subarrays I Array, Two Pointers, Binary Search, Enumeration
2974 Minimum Number Game Array, Sorting, Heap (Priority Queue), Simulation
2980 Check if Bitwise OR Has Trailing Zeros Array, Bit Manipulation
2996 Smallest Missing Integer Greater Than Sequential Prefix Sum Array, Hash Table, Sorting
3000 Maximum Area of Longest Diagonal Rectangle Array
3005 Count Elements With Maximum Frequency Array, Hash Table, Counting
3010 Divide an Array Into Subarrays With Minimum Cost I Array, Sorting, Enumeration
3014 Minimum Number of Pushes to Type Word I Math, String, Greedy
3019 Number of Changing Keys String
3024 Type of Triangle Array, Math, Sorting
3028 Ant on the Boundary Array, Simulation, Prefix Sum
3033 Modify the Matrix Array, Matrix
3038 Maximum Number of Operations With the Same Score I Array, Simulation
3042 Count Prefix and Suffix Pairs I Array, String, Trie, Rolling Hash, String Matching, Hash Function
3046 Split the Array Array, Hash Table, Counting
3065 Minimum Operations to Exceed Threshold Value I Array
3069 Distribute Elements Into Two Arrays I Array, Simulation
3074 Apple Redistribution into Boxes Array, Greedy, Sorting
3079 Find the Sum of Encrypted Integers Array, Math
3083 Existence of a Substring in a String and Its Reverse Hash Table, String
3090 Maximum Length Substring With Two Occurrences Hash Table, String, Sliding Window
3095 Shortest Subarray With OR at Least K I Array, Bit Manipulation, Sliding Window
3099 Harshad Number Math
3105 Longest Strictly Increasing or Strictly Decreasing Subarray Array
3110 Score of a String String
3114 Latest Time You Can Obtain After Replacing Characters String, Enumeration
3120 Count the Number of Special Characters I Hash Table, String
3127 Make a Square with the Same Color Array, Matrix, Enumeration
3131 Find the Integer Added to Array I Array
3136 Valid Word String
3142 Check if Grid Satisfies Conditions Array, Matrix
3146 Permutation Difference between Two Strings Hash Table, String
3151 Special Array I Array
3158 Find the XOR of Numbers Which Appear Twice Array, Hash Table, Bit Manipulation
3162 Find the Number of Good Pairs I Array, Hash Table
3168 Minimum Number of Chairs in a Waiting Room String, Simulation
3174 Clear Digits String, Stack, Simulation
3178 Find the Child Who Has the Ball After K Seconds Math, Simulation
3184 Count Pairs That Form a Complete Day I Array, Hash Table, Counting
3190 Find Minimum Operations to Make All Elements Divisible by Three Array, Math
3194 Minimum Average of Smallest and Largest Elements Array, Two Pointers, Sorting
3200 Maximum Height of a Triangle Array, Enumeration
3206 Alternating Groups I Array, Sliding Window
3210 Find the Encrypted String String
3216 Lexicographically Smallest String After a Swap String, Greedy
3222 Find the Winning Player in Coin Game Math, Simulation, Game Theory
3226 Number of Bit Changes to Make Two Integers Equal Bit Manipulation
3232 Find if Digit Game Can Be Won Array, Math
3238 Find the Number of Winning Players Array, Hash Table, Counting
3242 Design Neighbor Sum Service Array, Hash Table, Design, Matrix, Simulation
3248 Snake in Matrix Array, String, Simulation
3258 Count Substrings That Satisfy K-Constraint I String, Sliding Window
3264 Final Array State After K Multiplication Operations I Array, Math, Heap (Priority Queue), Simulation
3270 Find the Key of the Numbers Math
3274 Check if Two Chessboard Squares Have the Same Color Math, String
3280 Convert Date to Binary Math, String
3285 Find Indices of Stable Mountains Array
3289 The Two Sneaky Numbers of Digitville Array, Hash Table, Math
3300 Minimum Element After Replacement With Digit Sum Array, Math
3304 Find the K-th Character in String Game I Math, Bit Manipulation, Recursion, Simulation
3314 Construct the Minimum Bitwise Array I Array, Bit Manipulation
3318 Find X-Sum of All K-Long Subarrays I Array, Hash Table, Sliding Window, Heap (Priority Queue)
3330 Find the Original Typed String I String
3340 Check Balanced String String
3345 Smallest Divisible Digit Product I Math, Enumeration
3349 Adjacent Increasing Subarrays Detection I Array
3354 Make Array Elements Equal to Zero Array, Simulation, Prefix Sum
3360 Stone Removal Game Math, Simulation
3364 Minimum Positive Sum Subarray Array, Sliding Window, Prefix Sum
3370 Smallest Number With All Set Bits Math, Bit Manipulation
3375 Minimum Operations to Make Array Values Equal to K Array, Hash Table
3379 Transformed Array Array, Simulation
3386 Button with Longest Push Time Array
3392 Count Subarrays of Length Three With a Condition Array
3396 Minimum Number of Operations to Make Elements in Array Distinct Array, Hash Table
3402 Minimum Operations to Make Columns Strictly Increasing Array, Greedy, Matrix
3407 Substring Matching Pattern String, String Matching
3411 Maximum Subarray With Equal Products Array, Math, Sliding Window, Enumeration, Number Theory
3417 Zigzag Grid Traversal With Skip Array, Matrix, Simulation
3423 Maximum Difference Between Adjacent Elements in a Circular Array Array
3427 Sum of Variable Length Subarrays Array, Prefix Sum
3432 Count Partitions with Even Sum Difference Array, Math, Prefix Sum
3436 Find Valid Emails Database
3438 Find Valid Pair of Adjacent Digits in String Hash Table, String, Counting
3442 Maximum Difference Between Even and Odd Frequency I Hash Table, String, Counting
3452 Sum of Good Numbers Array
3456 Find Special Substring of Length K String
3461 Check If Digits Are Equal in String After Operations I Math, String, Simulation, Combinatorics, Number Theory
3465 Find Products with Valid Serial Numbers Database
3467 Transform Array by Parity Array, Sorting, Counting
3471 Find the Largest Almost Missing Integer Array, Hash Table
3477 Fruits Into Baskets II Array, Binary Search, Segment Tree, Simulation, Ordered Set
3483 Unique 3-Digit Even Numbers Array, Hash Table, Recursion, Enumeration
3487 Maximum Unique Subarray Sum After Deletion Array, Hash Table, Greedy
3492 Maximum Containers on a Ship Math
3498 Reverse Degree of a String String, Simulation
3502 Minimum Cost to Reach Every Position Array
3507 Minimum Pair Removal to Sort Array I Array, Hash Table, Linked List, Heap (Priority Queue), Simulation, Doubly-Linked List, Ordered Set
3512 Minimum Operations to Make Array Sum Divisible by K Array, Math
3516 Find Closest Person Math
3536 Maximum Product of Two Digits Math, Sorting
3541 Find Most Frequent Vowel and Consonant Hash Table, String, Counting
3545 Minimum Deletions for At Most K Distinct Characters Hash Table, String, Greedy, Sorting, Counting
3550 Smallest Index With Digit Sum Equal to Index Array, Math
3560 Find Minimum Log Transportation Cost Math
3570 Find Books with No Available Copies Database
3582 Generate Tag for Video Caption String, Simulation
3591 Check if Any Element Has Prime Frequency Array, Hash Table, Math, Counting, Number Theory
3602 Hexadecimal and Hexatrigesimal Conversion Math, String
3606 Coupon Code Validator Array, Hash Table, String, Sorting
3622 Check Divisibility by Digit Sum and Product Math
3633 Earliest Finish Time for Land and Water Rides I -
3637 Trionic Array I -