| 3 |
Longest Substring Without Repearing Characters |
Python3 |
Medium |
Sliding Window |
| 13 |
Roman to Integer |
Python3 |
Easy |
|
| 20 |
Valid Parentheses |
Java |
Easy |
|
| 40 |
Combination Sum II |
Python3 |
Medium |
|
| 41 |
First Missing Positive |
C |
Hard |
|
| 42 |
Trapping Rain Water |
Python3 |
Hard |
Solution using arrays
Solution using two pointers |
| 50 |
Pow(x, n) |
Python3 |
Medium |
|
| 56 |
Merge Intervals |
Python3 |
Medium |
|
| 69 |
Sqrt(x) |
Java |
Easy |
|
| 75 |
Sort Colors |
Python3 |
Medium |
Counting Sort (two-pass),
Two pointers (one-pass) |
| 78 |
Subsets |
Python3 |
Medium |
|
| 94 |
Binary Tree Inorder Traversal |
Java |
Easy |
|
| 118 |
Pascal's Triangle |
Python3 |
Easy |
|
| 131 |
Palindrome Partitioning |
Python3 |
Medium |
|
| 136 |
Single Number |
C |
Easy |
|
| 137 |
Single Number II |
C |
Medium |
|
| 140 |
Word Break II |
Python3 |
Hard |
|
| 141 |
Linked List Cycle |
Java |
Easy |
|
| 145 |
Binary Tree Postorder Traversal |
Python3 |
Easy |
|
| 146 |
LRU Cache |
Python3 |
Medium |
Ordered Dictionary, Doubly Linked List & Hashmap |
| 165 |
Compare Version Numbers |
Python3 |
Medium |
|
| 179 |
Largest Number |
Python3 |
Medium |
|
| 200 |
Number of Islands |
Python3 |
Medium |
BFS on a matrix |
| 206 |
Reverse Linked List |
C |
Easy |
|
| 214 |
Shortest Palindrome |
Python3 |
Hard |
Rabin–Karp algorithm |
| 215 |
Kth Largest Element in an Array |
Python3 |
Medium |
One liner |
| 237 |
Delete Node in a Linked List |
Python3 |
Medium |
|
| 241 |
Different Ways to Add Parentheses |
Python3 |
Medium |
|
| 260 |
Single Number III |
C |
Medium |
|
| 264 |
Ugly Number II |
Python3 |
Medium |
Mathematical properties |
| 273 |
Integer to English Words |
Python3 |
Hard |
|
| 287 |
Find the Duplicate Number |
C |
Medium |
Floyd's cycle detection |
| 330 |
Patching Array |
Python3 |
Hard |
Mathematical properties |
| 338 |
Counting Bits |
C |
Easy |
|
| 344 |
Reverse String |
C |
Easy |
|
| 350 |
Intersection of Two Arrays II |
Python3 |
Easy |
|
| 386 |
Lexicographical Numbers |
Python3 |
Medium |
|
| 409 |
Longest Palindrome |
Python3 |
Easy |
|
| 432 |
All O`one Data Structure |
Python3 |
Medium |
|
| 440 |
K-th Smallest in Lexicographical Order |
Python3 |
Hard |
|
| 476 |
Number Complement |
Python3 |
Easy |
|
| 502 |
IPO |
Python3 |
Hard |
|
| 506 |
Relative Ranks |
Python3 |
Easy |
|
| 523 |
Continuous Subarray Sum |
Java |
Medium |
Mathematical properties |
| 539 |
Minimum Time Difference |
Python3 |
Medium |
|
| 552 |
Student Attendance Record II |
Java |
Hard |
|
| 564 |
Find the Closest Palindrome |
Python3 |
Hard |
|
| 567 |
Permutation in String |
Java |
Medium |
|
| 590 |
N-ary Tree Postorver Traversal |
Python3 |
Easy |
|
| 592 |
Fraction Addition and Subtraction |
Python3 |
Medium |
|
| 624 |
Maximum Distance in Arrays |
Python3 |
Medium |
|
| 632 |
Smallest Range Covering Elements from K Lists |
Python3 |
Hard |
|
| 633 |
Sum of Square Numbers |
Python3 |
Medium |
Mathematical properties |
| 641 |
Design Circular Deque |
Python3 |
Medium |
|
| 648 |
Replace Words |
Python3 |
Medium |
|
| 650 |
2 Keys Keyboard |
Python3 |
Medium |
Dynamic Programming |
| 664 |
Strange Printer |
Python3 |
Hard |
Dynamic Programming |
| 670 |
Maximum Swap |
Python3 |
Medium |
|
| 703 |
Kth Largest Element in a Stream |
Python3 |
Easy |
|
| 719 |
Find K-th Smallest Pair Distance |
Python3 |
Hard |
Sliding Window & Binary Search on the result |
| 725 |
Split Linked List in Parts |
Python3 |
Medium |
|
| 726 |
Number of Atoms |
Python3 |
Hard |
Parsing string |
| 729 |
My Calendar I |
Python3 |
Medium |
|
| 731 |
My Calendar II |
Python3 |
Medium |
|
| 771 |
Jewels and Stones |
Python3 |
Easy |
|
| 773 |
Sliding Puzzle |
Python3 |
Hard |
|
| 786 |
K-th Smallest Prime Fraction |
C |
Medium |
|
| 796 |
Rotate String |
Java |
Easy |
|
| 826 |
Most Profit Assigning Work |
Python3 |
Medium |
|
| 840 |
Magic Squares In Grid |
Python3 |
Medium |
|
| 846 |
Hand of Straights |
Python3 |
Medium |
|
| 857 |
Minimum Cost to Hire K Workers |
Python3 |
Hard |
|
| 860 |
Lemonade Change |
Python3 |
Easy |
|
| 861 |
Score After Flipping Matrix |
Python3 |
Medium |
|
| 862 |
Shortest Subarray with Sum at Least K |
Python3 |
Hard |
|
| 874 |
Walking Robot Simulation |
Python3 |
Medium |
|
| 881 |
Boats to Save People |
Python3 |
Medium |
|
| 884 |
Uncommon Words from Two Sentences |
Python3 |
Easy |
|
| 885 |
Spiral Matrix III |
Python3 |
Medium |
|
| 912 |
Sort an Array |
Python3 |
Medium |
Implement sorting algorithm without built-in functions.
Merge Sort, Heap Sort, Counting Sort |
| 921 |
Minimum Add to Make Parentheses Valid |
Python3 |
Medium |
|
| 938 |
Range Sum of BST |
C |
Easy |
|
| 945 |
Minimum Increment to Make Array Unique |
Python3 |
Medium |
|
| 947 |
Most Stones Removed with Same Row or Column |
Python3 |
Medium |
Union Find |
| 951 |
Flip Equivalent Binary Trees |
Python3 |
Medium |
|
| 959 |
Regions Cut By Slashes |
Python3 |
Medium |
Question can be mapped to Number of Islands (#200) |
| 962 |
Maximum Width Ramp |
Python3 |
Medium |
|
| 973 |
K Closest Points to Origin |
Python3 |
Medium |
Heap / sort by lambda function |
| 974 |
Subarray Sum Divisible by K |
Java, Python3 |
Medium |
|
| 979 |
Distribute Coins in Binary Tree |
C |
Medium |
DFS |
| 995 |
Minimum Number of K Consecutive Bit Flips |
Python3 |
Hard |
Sliding Window &
Bit Manipulation
Great editorial |
| 1002 |
Find Common Characters |
Java |
Easy |
|
| 1038 |
Binary Search Tree to Greater Sum Tree |
Python3 |
Medium |
BST, DFS |
| 1051 |
Height Checker |
Java, Python3 |
Easy |
Counting Sort |
| 1052 |
Grumpy Bookstore Owner |
Python3 |
Medium |
Sliding Window |
| 1072 |
Flip Columns for Maximum Number of Equal Rows |
Python3 |
Medium |
|
| 1105 |
Filling Bookcase Shelves |
Python3 |
Medium |
Dynamic Programming |
| 1106 |
Parsing A Boolean Expression |
Python3 |
Hard |
|
| 1110 |
Delete Nodes and Return Forest |
Python3 |
Medium |
|
| 1122 |
Relative Sort Array |
Python3 |
Easy |
|
| 1140 |
Stone Game II |
Python3 |
Medium |
Dynamic Programming |
| 1190 |
Reverse Substrings Between Each Pair of Parentheses |
Python3 |
Medium |
|
| 1208 |
Get Equal Substrings Within Budget |
C |
Medium |
Sliding Window |
| 1219 |
Path with Maximum Gold |
Java |
Medium |
DFS & Backtracking |
| 1233 |
Remove Sub-Folders from the Filesystem |
Python3 |
Medium |
|
| 1248 |
Count Number of Nice Subarrays |
Python3 |
Medium |
Sliding Window |
| 1255 |
Maximum Score Words Formed by Letters |
C |
Hard |
|
| 1268 |
Search Suggestions System |
Python3 |
Medium |
|
| 1277 |
Count Square Submatrices with All Ones |
Python3 |
Medium |
|
| 1310 |
XOR Queries of a Subarray |
Python3 |
Medium |
|
| 1325 |
Delete Leaves With a Given Value |
C |
Medium |
DFS |
| 1331 |
Rank Transform of an Array |
Java |
Easy |
|
| 1334 |
Find the City With the Smallest Number of Neighbors at a Threshold Distance |
Python3 |
Medium |
Shortest Path from every node to every node.
Dijkstra's algorithm, Floyd-Warshall algorithm |
| 1342 |
Number of Steps to Reduce a Number to Zero |
Python3 |
Easy |
|
| 1367 |
Linked List in Binary Tree |
Python3 |
Medium |
|
| 1371 |
Find the Longest Substring Containing Vowels in Even Counts |
Python3 |
Medium |
|
| 1380 |
Lucky Numbers in a Matrix |
Python3 |
Easy |
|
| 1381 |
Design a Stack With Increment Operation |
Python3, Java |
Medium |
|
| 1382 |
Balance a Binary Search Tree |
Python3 |
Medium |
|
| 1395 |
Count Number of Teams |
Python3 |
Medium |
|
| 1404 |
Number of Steps to Reduce a Number in Binary Representation to One |
C |
Medium |
|
| 1405 |
Longest Happy String |
Python3 |
Medium |
|
| 1438 |
Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit |
Python3 |
Medium |
Sliding Window with 2 Heaps |
| 1442 |
Count Triplets That Can Form Two Arrays of Equal XOR |
C |
Medium |
|
| 1460 |
Make Two Arrays Equal by Reversing Subarrays |
Python3 |
Easy |
|
| 1480 |
Running Sum of 1d Array |
Java |
Easy |
|
| 1482 |
Minimum Number of Days to Make m Bouquets |
Python3 |
Medium |
|
| 1486 |
XOR Operation in an Array |
Python3 |
Easy |
|
| 1497 |
Check If Array Pairs Are Divisible by K |
Java |
Medium |
|
| 1508 |
Range Sum of Sorted Subarray Sums |
Python3 |
Medium |
|
| 1509 |
Minimum Difference Between Largest and Smallest Value in Three Moves |
Python3 |
Medium |
|
| 1512 |
Number of Good Pairs |
Go |
Easy |
|
| 1514 |
Path with Maximum Probability |
Python3 |
Medium |
Maximizing probability instead of minimizing distance.
Dijkstra's algorithm, Bellman-Ford algorithm |
| 1518 |
Water Bottles |
Python3 |
Easy |
Mathematical properties |
| 1530 |
Number of Good Leaf Nodes Pairs |
Python3 |
Medium |
DFS, Shortest Path between nodes |
| 1545 |
Find Kth Bit in Nth Binary String |
Python3 |
Medium |
|
| 1550 |
Three Consecutive Odds |
Python3 |
Easy |
|
| 1552 |
Magnetic Force Between Two Balls |
Python3 |
Medium |
Binary Search |
| 1568 |
Minimum Number of Days to Disconnect Island |
Python3 |
Hard |
|
| 1574 |
Shortest Subarray to be Removed to Make Array Sorted |
Python3 |
Medium |
|
| 1579 |
Remove Max Number of Edges to Keep Graph Fully Traversable |
Python3 |
Hard |
Union Find, Graph |
| 1590 |
Make Sum Divisible by P |
Java |
Medium |
|
| 1593 |
Split a String Into the Max Number of Unique Substrings |
Python3 |
Medium |
|
| 1598 |
Crawler Log Folder |
Python3 |
Easy |
|
| 1605 |
Find Valid Matrix Given Row and Column Sums |
Python3 |
Medium |
|
| 1608 |
Special Array With X Elements Greater Than or Equal X |
Python3, C |
Easy |
Python3: Sorting
C: Suffix Sum |
| 1636 |
Sort Array by Increasing Frequency |
Python3 |
Easy |
|
| 1641 |
Count Sorted Vowel Strings |
Python3 |
Medium |
Dynamic Programming |
| 1652 |
Defuse the Bomb |
Python3 |
Easy |
|
| 1653 |
Minimum Deletions to Make String Balanced |
Python3 |
Medium |
|
| 1671 |
Minimum Number of Removals to Make Mountain Array |
Python3 |
Hard |
|
| 1684 |
Count the Number of Consistent Strings |
Python3, Java |
Easy |
|
| 1689 |
Partitioning Into Minimum Number of Deci-Binary Numbers |
Java |
Medium |
|
| 1701 |
Average Waiting Time |
Python3 |
Medium |
|
| 1717 |
Maximum Score From Removing Substrings |
Python3 |
Medium |
|
| 1720 |
Decode XORed Array |
Python3 |
Easy |
|
| 1791 |
Find Center of Star Graph |
Python3 |
Easy |
|
| 1813 |
Sentence Similarity III |
Python3 |
Medium |
|
| 1823 |
Find the Winner of the Circular Game |
Python3 |
Medium |
Mathematical properties |
| 1829 |
Maximum XOR for Each Query |
Java |
Medium |
|
| 1861 |
Rotating the Box |
Python3 |
Medium |
|
| 1863 |
Sum of All Subset XOR Totals |
Java, C |
Easy |
Java: trivial, inefficient
C: Black magic AKA bit manipulation |
| 1894 |
Find the Student that Will Replace the Chalk |
Python3 |
Medium |
|
| 1905 |
Count Sub Islands |
Python3 |
Medium |
|
| 1937 |
Maximum Number of Points with Cost |
Python3 |
Medium |
Dynamic Programming |
| 1942 |
The Number of the Smallest Unoccupied Chair |
Python3 |
Medium |
Two heaps |
| 1945 |
Sum of Digits of String After Convert |
Python3 |
Easy |
|
| 1957 |
Delete Characters to Make Fancy String |
Python3 |
Easy |
|
| 1963 |
Minimum Number of Swaps to Make the String Balanced |
Python3 |
Medium |
|
| 1975 |
Maximum Matrix Sum |
Python3 |
Medium |
|
| 2000 |
Reverse Prefix of Word |
C |
Easy |
|
| 2022 |
Convert 1D Array Into 2D Array |
Python3 |
Easy |
|
| 2028 |
Find Missing Observations |
Python3 |
Medium |
Mathematical properties |
| 2037 |
Minimum Number of Moves to Seat Everyone |
Python3 |
Easy |
|
| 2044 |
Count Number of Maximum Bitwise-OR Subsets |
Python3 |
Medium |
|
| 2045 |
Second Minimum Time to Reach Destination |
Python3 |
Hard |
BFS with extra conditions |
| 2053 |
Kth Distinct String in an Array |
Python3 |
Easy |
|
| 2058 |
Find the Minimum and Maximum Number of Nodes Between Critical Points |
Python3 |
Medium |
|
| 2064 |
Minimized Maximum of Products Distributed to Any Store |
Python3 |
Medium |
|
| 2070 |
Most Beautiful Item for Each Query |
Python3 |
Medium |
|
| 2096 |
Step-By-Step Direction From a Binary Tree Node to Another |
Python3 |
Medium |
BFS |
| 2134 |
Minimum Swaps to Group All 1's Together II |
Python3 |
Medium |
|
| 2181 |
Merge Nodes in Between Zeros |
Python3 |
Medium |
|
| 2191 |
Sort the Jumbled Numbers |
Python3 |
Medium |
|
| 2192 |
All Ancestors of a Node in a Directed Acyclic Graph |
Python3 |
Medium |
|
| 2196 |
Create Binary Tree From Descriptions |
Python3 |
Medium |
|
| 2220 |
Minimum Bit Flips to Convert Number |
Python3, Java |
Easy |
|
| 2248 |
Intersection of Multiple Arrays |
Python3 |
Easy |
|
| 2257 |
Count Unguarded Cells in the Grid |
Python3 |
Medium |
|
| 2275 |
Largest Combination With Bitwise AND Greater Than Zero |
Java |
Medium |
|
| 2285 |
Maximum Total Importance of Roads |
Python3 |
Medium |
Undirected Graph, Greedy |
| 2326 |
Spiral Matrix IV |
Python3 |
Medium |
|
| 2331 |
Evaluate Boolean Binary Tree |
C |
Easy |
|
| 2373 |
Largest Local Value in a Matrix |
Java |
Easy |
|
| 2392 |
Build a Matrix With Conditions |
Python3 |
Hard |
Topological Sort, DFS |
| 2406 |
Divide Intervals Into Minimum Number of Groups |
Python3 |
Medium |
|
| 2416 |
Sum of Prefix Scores of Strings |
Python3 |
Hard |
Trie / Prefix Tree |
| 2418 |
Sort the People |
Python3 |
Easy |
|
| 2419 |
Longest Subarray With Maximum Bitwise AND |
Python3 |
Medium |
|
| 2441 |
Largest Positive Integer That Exists With Its Negative |
Python3 |
Easy |
|
| 2458 |
Height of Binary Tree After Subtree Removal Queries |
Python3 |
Hard |
|
| 2461 |
Maximum Sum of Distinct Subarrays With Length K |
Python3 |
Medium |
|
| 2463 |
Minimum Total Distance Traveled |
Python3 |
Hard |
|
| 2469 |
Convert the Temperature |
Go |
Easy |
|
| 2486 |
Append Characters to String to Make Subsequence |
C |
Medium |
|
| 2487 |
Remove Nodes From Linked List |
Java |
Medium |
Monotonic Stack |
| 2490 |
Circular Sentence |
Python3 |
Easy |
|
| 2491 |
Divide Players Into Teams of Equal Skill |
Java |
Medium |
|
| 2501 |
Longest Square Streak in an Array |
Python3 |
Medium |
|
| 2516 |
Take K of Each Character From Left and Right |
Python3 |
Medium |
|
| 2530 |
Maximal Score After Applying K Operations |
Python3 |
Medium |
|
| 2563 |
Count the Number of Fair Pairs |
Python3 |
Medium |
|
| 2574 |
Left and Right Sum Differences |
Java |
Easy |
|
| 2582 |
Pass the Pillow |
Python3 |
Easy |
Mathematical properties |
| 2583 |
Kth Largest Sum in a Binary Tree |
Python3 |
Medium |
|
| 2597 |
The Number of Beautiful Subsets |
Python3 |
Medium |
Backtracking |
| 2601 |
Prime Subtraction Operation |
Python3 |
Medium |
|
| 2641 |
Cousins in Binary Tree II |
Python3 |
Medium |
|
| 2657 |
Find the Prefix Common Array of Two Arrays |
Java |
Medium |
|
| 2678 |
Number of Senior Citizens |
Python3 |
Easy |
|
| 2684 |
Maximum Number of Moves in a Grid |
Python3, Java |
Medium |
|
| 2696 |
Minimum String Length After Removing Substrings |
Python3 |
Easy |
|
| 2699 |
Modify Graph Edge Weights |
Python3 |
Hard |
Dijkstra's algorithm |
| 2707 |
Extra Characters in a String |
Python3 |
Medium |
Trie / Prefix Tree |
| 2751 |
Robot Collisions |
Python3 |
Hard |
|
| 2807 |
Insert Greatest Common Divisors in Linked List |
Python3 |
Medium |
|
| 2812 |
Find the Safest Path in a Grid |
Java |
Medium |
Multi-source BFS |
| 2816 |
Double a Number Represented as a Linked List |
C |
Medium |
|
| 2859 |
Sum of Values at Indices With K Set Bits |
Python3 |
Easy |
|
| 2886 |
Change Data Type |
Python3 |
Easy |
|
| 2914 |
Minimum Number of Changes to Make Binary String Beautiful |
Python3 |
Medium |
|
| 2924 |
Find Champion II |
Python3 |
Medium |
|
| 2938 |
Separate Black and White Balls |
Python3 |
Medium |
|
| 2952 |
Minimum Number of Coins to be Added |
Python3 |
Medium |
Mathematical properties |
| 2976 |
Minimum Cost to Convert String I |
Python3 |
Medium |
Dijkstra's algorithm, Floyd-Warshall algorithm |
| 3011 |
Find if Array Can Be Sorted |
Java |
Medium |
|
| 3016 |
Minimum Number of Pushes to Type Word II |
Python3 |
Medium |
|
| 3043 |
Find the Length of the Longest Common Prefix |
Python3 |
Medium |
|
| 3068 |
Find the Maximum Sum of Node Values |
C |
Hard |
|
| 3075 |
Maximize Happiness of Selected Children |
Java, Python3 |
Medium |
Java: Max Heap
Python3: Sorting |
| 3097 |
Shortest Subarray With OR at Least K II |
Python3 |
Medium |
|
| 3110 |
Score of a String |
Java |
Easy |
|
| 3133 |
Minimum Array End |
Java |
Medium |
|
| 3163 |
String Compression III |
Python3 |
Medium |
|
| 3217 |
Delete Nodes From Linked List Present in Array |
Python3 |
Medium |
|
| 3254 |
Find the Power of K-Size Subarrays I |
Python3 |
Medium |
|