| 5 |
Longest Palindromic Substring |
Python3 |
Medium |
Many solutions here |
| 19 |
Remove Nth Node From End of List |
Python3 |
Medium |
|
| 24 |
Swap Nodes in Pairs |
Python3 |
Medium |
|
| 33 |
Search in Rotated Sorted Array |
Python3 |
Medium |
|
| 34 |
Find First and Last Position of Element in Sorted Array |
Python3 |
Medium |
|
| 35 |
Search Insert Position |
Python3 |
Easy |
|
| 38 |
Count and Say |
Python3 |
Easy |
|
| 49 |
Group Anagrams |
Python3 |
Medium |
|
| 61 |
Rotate List |
Python3 |
Medium |
|
| 69 |
Sqrt(x) |
Python3 |
Easy |
|
| 74 |
Search a 2D Matrix |
Python3 |
Medium |
|
| 82 |
Remove Duplicates from Sorted List II |
Python3 |
Medium |
|
| 83 |
Remove Duplicates from Sorted List |
Python3 |
Easy |
|
| 84 |
Largest Rectangle in Histogram |
Python3 |
Hard |
|
| 85 |
Maximal Rectangle |
Python3[1, 2] |
Hard |
|
| 92 |
Reverse Linked List II |
Python3 |
Medium |
|
| 94 |
Binary Tree Inorder Traversal |
Python3 |
Medium |
|
| 95 |
Unique Binary Search Trees II |
Python3 |
Medium |
Refer to here |
| 96 |
Unique Binary Search Trees |
Python3 |
Medium |
|
| 97 |
Interleaving String |
Python3 |
Hard |
|
| 98 |
Validate Binary Search Tree |
Python3[1, 2] |
Medium |
Solution 2 refers to here |
| 99 |
Recover Binary Search Tree |
Python3 |
Hard |
Refer to this thinking |
| 100 |
Same Tree |
Python3 |
Easy |
|
| 101 |
Symmetric Tree |
Python3[1, 2] |
Easy |
I think it should be Medium |
| 102 |
Binary Tree Level Order Traversal |
Python3 |
Medium |
|
| 103 |
Binary Tree Zigzag Level Order Traversal |
Python3 |
Medium |
Similar with 102 |
| 104 |
Maximum Depth of Binary Tree |
Python3 |
Easy |
|
| 105 |
Construct Binary Tree from Preorder and Inorder Traversal |
Python3 |
Medium |
|
| 106 |
Construct Binary Tree from Inorder and Postorder Traversal |
Python3 |
Medium |
|
| 107 |
Binary Tree Level Order Traversal II |
Python3 |
Easy |
Similar with 102 |
| 108 |
Convert Sorted Array to Binary Search Tree |
Python3 |
Easy |
|
| 109 |
Convert Sorted List to Binary Search Tree |
Python3 |
Medium |
|
| 110 |
Balanced Binary Tree |
Python3 |
Easy |
|
| 111 |
Minimum Depth of Binary Tree |
Python3 |
Easy |
A little entrap |
| 116 |
Populating Next Right Pointers in Each Node |
Python3 |
Medium |
|
| 146 |
LRU Cache |
Python3[1, 2] |
Hard |
Solution2 use OrderedDict |
| 151 |
Reverse Words in a String |
Python3 |
Medium |
Maybe it is 'Easy'. |
| 153 |
Find Minimum in Rotated Sorted Array |
Python3 |
Medium |
|
| 160 |
Intersection of Two Linked Lists |
Python3 |
Easy |
Refer to here, two pointer solution |
| 165 |
Compare Version Numbers |
Python3 |
Medium |
|
| 168 |
Excel Sheet Column Title |
Python3 |
Easy |
*Recursion. It is more than 'Easy'! |
| 172 |
Factorial Trailing Zeroes |
Python3 |
Easy |
There's a conclusion about factorial |
| 206 |
Reverse Linked List |
Python3 |
Easy |
|
| 236 |
Lowest Common Ancestor of a Binary Tree |
Python3 |
Medium |
|
| 237 |
Delete Node in a Linked List |
Python3 |
Easy |
|
| 257 |
Binary Tree Paths |
Python3 |
Easy |
|
| 283 |
Move Zeroes |
Python3 |
Easy |
|
| 301 |
Remove Invalid Parentheses |
Python3 |
Hard |
|
| 330 |
Patching Array |
Python3 |
Hard |
Greedy, refer to here |
| 341 |
Flatten Nested List Iterator |
Python3 |
Medium |
|
| 378 |
Kth Smallest Element in a Sorted Matrix |
Python3 |
Medium |
Binary Search |
| 395 |
Longest Substring with At Least K Repeating Characters |
Python3 |
Medium |
Divide and Conquer |
| 414 |
Third Maximum Number |
Python3[1, 2] |
Easy |
|
| 433 |
Minimum Genetic Mutation |
Python3 |
Medium |
Breadth-first Search |
| 435 |
Non-overlapping Intervals |
C++ |
Medium |
Greedy |
| 463 |
Island Perimeter |
Python3 |
Easy |
|
| 468 |
Validate IP Address |
Python3 |
Medium |
|
| 473 |
Matchsticks to Square |
Python3, C++ |
Medium |
Refer to official solution |
| 522 |
Longest Uncommon Subsequence II |
Python3 |
Medium |
|
| 543 |
Diameter of Binary Tree |
Python3 |
Easy |
|
| 600 |
Non-negative Integers without Consecutive Ones |
Python3 |
Hard |
Dynamic programming, bit dp |
| 647 |
Palindromic Substrings |
Python3[1, 2] |
Medium |
Solution 2 refers to here |
| 665 |
Non-decreasing Array |
Python3 |
Easy |
|
| 695 |
Max Area of Island |
Python3 |
Medium |
|
| 773 |
Sliding Puzzle |
Python3 |
Hard |
|
| 793 |
Preimage Size of Factorial Zeroes Function |
Python3 |
Hard |
Refer to here |
| 797 |
All Paths From Source to Target |
Python3 |
Medium |
|
| 802 |
Find Eventual Safe States |
Python3 |
Medium |
Refer to here |
| 805 |
Split Array With Same Average |
Python3 |
Hard |
Refer to here |
| 825 |
Friends Of Appropriate Ages |
Python3[1, 2] |
Medium |
Solution 2 refers to here |
| 851 |
Loud and Rich |
Python3 |
Medium |
Depth-first |
| 855 |
Exam Room |
C++ |
Medium |
Refer to here |
| 876 |
Middle of the Linked List |
Python3 |
Easy |
|
| 880 |
Decoded String at Index |
Python3[1, 2] |
Medium |
Solution 2 refers to here |
| 893 |
Groups of Special-Equivalent Strings |
Python3 |
Easy |
Refer to here |
| 898 |
Bitwise ORs of Subarrays |
Python3[1, 2] |
Medium |
Solution 2 refers to here |
| 929 |
Unique Email Addresses |
Python3 |
Easy |
|
| 954 |
Array of Doubled Pairs |
Python3 |
Medium |
|
| 967 |
Numbers With Same Consecutive Differences |
Python3 |
Medium |
|
| 1005 |
Maximize Sum Of Array After K Negations |
Python3 |
Easy |
|
| 1006 |
Clumsy Factorial |
Python3 |
Medium |
|
| 1007 |
Minimum Domino Rotations For Equal Row |
Python3 |
Medium |
|
| 1008 |
Construct Binary Search Tree from Preorder Traversal |
Python3 |
Medium |
|
| 1037 |
Valid Boomerang |
C++ |
Easy |
|
| 1275 |
Find Winner on a Tic Tac Toe Game |
Python3 |
Easy |
|
| 1276 |
Number of Burgers with No Waste of Ingredients |
Python3 |
Medium |
It should be Easy |
| 1277 |
Count Square Submatrices with All Ones |
Python3 |
Medium |
DP Algorithm |
| 1281 |
Subtract the Product and Sum of Digits of an Integer |
Python3 |
Easy |
|
| 1282 |
Group the People Given the Group Size They Belong To |
Python3[1, 2] |
Medium |
Solution2 uses HashMap, refer to here |
| 1283 |
Find the Smallest Divisor Given a Threshold |
Python3 |
Medium |
|
| 1284 |
Minimum Number of Flips to Convert Binary Matrix to Zero Matrix |
Python3 |
Hard |
Enumeration Method |
| 1290 |
Convert Binary Number in a Linked List to Integer |
Python3 |
Easy |
|
| 1291 |
Sequential Digits |
Python3 |
Medium |
Enumeration |
| 1292 |
Maximum Side Length of a Square with Sum Less than or Equal to Threshold |
Python3[1, 2] |
Medium |
Solution 2 uses a tricky optimization, refers to here |
| 1293 |
Shortest Path in a Grid with Obstacles Elimination |
Python3[1, 2] |
Hard |
Solution 1 is DFS+pruning, solution 2 refers to here |
| 1323 |
Maximum 69 Number |
CPP |
|
|
| 1328 |
Break a Palindrome |
Python3 |
Medium |
|
| 1329 |
Sort the Matrix Diagonally |
Python3 |
Medium |
|
| 1330 |
Reverse Subarray To Maximize Array Value |
Python3[1, 2] |
Hard |
Solution 1 refers to here |
| 1331 |
Rank Transform of an Array |
Python3 |
Easy |
|
| 1332 |
Remove Palindromic Subsequences |
Python3 |
Easy |
puzzling |
| 1333 |
Filter Restaurants by Vegan-Friendly, Price and Distance |
Python3 |
Medium |
|
| 1334 |
Find the City With the Smallest Number of Neighbors at a Threshold Distance |
Python3 |
Medium |
|
| 1335 |
Minimum Difficulty of a Job Schedule |
Python3 |
Hard |
DFS+Memoization |
| 1341 |
The K Weakest Rows in a Matrix |
Python3 |
Easy |
|
| 1342 |
Reduce Array Size to The Half |
Python3 |
Medium |
|
| 1343 |
Maximum Product of Splitted Binary Tree |
Python3 |
Medium |
|
| DFS+Memoization1344 |
Jump Game V |
Python3 |
Hard |
DFS+Memoization |
| 1346 |
Check If N and Its Double Exist |
Python3 |
Easy |
|
| 1347 |
Minimum Number of Steps to Make Two Strings Anagram |
Python3 |
Medium |
|
| 1348 |
Tweet Counts Per Frequency |
Python3 |
Medium |
|
| 1349 |
Maximum Students Taking Exam |
Python3 |
Hard |
State compression DP, refer to here |
| 1351 |
Count Negative Numbers in a Sorted Matrix |
Python3 |
Easy |
|
| 1352 |
Product of the Last K Numbers |
Python3 |
Medium |
refer to here |
| 1353 |
Maximum Number of Events That Can Be Attended |
Python3 |
Medium |
Greedy, refer to here |
| 1354 |
Construct Target Array With Multiple Sums |
Python3 |
Hard |
|
| 1360 |
Number of Days Between Two Dates |
Python3 |
Easy |
|
| 1361 |
Validate Binary Tree Nodes |
Python3 |
Medium |
|
| 1362 |
Closest Divisors |
Python3 |
Medium |
|
| 1389 |
Create Target Array in the Given Order |
Python3 |
Easy |
|
| 1390 |
Four Divisors |
Python3 |
Medium |
|
| 1391 |
Check if There is a Valid Path in a Grid |
Python3 |
Medium |
|
| 1392 |
Longest Happy Prefix |
Python3 |
Hard |
|
| 5291 |
Find Numbers with Even Number of Digits |
Python3 |
Easy |
|
| 5292 |
Divide Array in Sets of K Consecutive Numbers |
Python3 |
Medium |
|
| 5293 |
Maximum Number of Occurrences of a Substring |
Python3 [1, 2] |
Medium |
Solution 2 uses sliding window and unordered dict, which is faster. Refer to here |
| 5294 |
Maximum Candies You Can Get from Boxes |
Python3 [1, 2] |
Hard |
Solution uses BFS, refer to here |