1. |
Two Sum |
Python |
Easy |
|
1. |
Two Sum |
Python |
Easy |
optimized soln |
2. |
Add Two Numbers |
Python |
Medium |
Linked List + brute force |
3. |
Longest Substring Without Repeating Characters |
Python |
Medium |
Kinda brute force |
4. |
Median of Two Sorted Arrays |
Python |
Hard |
|
5. |
Longest Palindromic Substring |
Python |
Medium |
Brute Force |
7. |
Reverse Integer |
Python |
Easy |
|
9. |
Palindrome Number |
Python |
Easy |
Without converting integer into string |
11. |
Container With Most Water |
Python |
Medium |
Two Pointers |
12. |
Integer to Roman |
Python |
Medium |
|
13. |
Roman to Integer |
Python |
Easy |
|
14. |
Longest Common Prefix |
Python |
Easy |
|
15. |
3Sum |
Python |
Medium |
Brute Force |
16. |
3Sum Closest |
Python |
Medium |
Brute Force |
17. |
Letter Combinations of a Phone Number |
Python |
Medium |
DFS , Recursion |
19. |
Remove Nth Node From End of List |
Python |
Medium |
Stack |
20. |
Valid Parentheses |
Python |
Easy |
Brute Force |
20. |
Valid Parentheses |
Python |
Easy |
Stack |
21. |
Merge Two Sorted Lists |
Python |
Easy |
Linked List |
23. |
Merge k Sorted Lists |
Python |
Hard |
Linked List , not exactly what was aked |
24. |
Swap Nodes in Pairs |
Python |
Medium |
Linked List |
25. |
Reverse Nodes in k-Group |
Python |
Hard |
Linked List , Stack |
26. |
Remove Duplicates from Sorted Array |
Python |
Easy |
Several solutions in one file |
27. |
Remove Element |
Python |
Easy |
|
29. |
Divide Two Integers |
Python |
Medium |
|
33. |
Search in Rotated Sorted Array |
Python |
Medium |
|
34. |
Find First and Last Position of Element in Sorted Array |
Python |
Medium |
Binary Search |
34. |
Find First and Last Position of Element in Sorted Array |
Python |
Medium |
|
35. |
Search Insert Position |
Python |
Easy |
Binary Search |
36. |
Valid Sudoku |
Python |
Medium |
Brute Force, set , list |
41. |
First Missing Positive |
Python |
Hard |
|
46. |
Permutations |
Python |
Medium |
Itertools |
47. |
Permutations II |
Python |
Medium |
Itertools |
48. |
Rotate Image |
Python |
Medium |
|
49. |
Group Anagrams |
Python |
Medium |
|
50. |
Pow(x, n) |
Python |
Medium |
Recursion |
53. |
Maximum Subarray |
Python |
Easy |
|
54. |
Spiral Matrix |
Python |
Medium |
|
55. |
Jump Game |
Python |
Medium |
|
56. |
Merge Intervals |
Python |
Medium |
|
57. |
Insert Interval |
Python |
Hard |
|
58. |
Length of Last Word |
Python |
Easy |
List |
58. |
Length of Last Word |
Python |
Easy |
String |
59. |
Spiral Matrix II |
Python |
Medium |
spaghetti |
61. |
Rotate List |
Python |
Medium |
Linked List |
63. |
Unique Paths II |
Python |
Medium |
DP |
64. |
Minimum Path Sum |
Python |
Medium |
|
66. |
Plus One |
Python |
Easy |
|
67. |
Add Binary |
Python |
Easy |
|
71. |
Simplify Path |
Python |
Medium |
Stack |
73. |
Set Matrix Zeroes |
Python |
Medium |
set() |
74. |
Search a 2D Matrix |
Python |
Medium |
Binary Search |
75. |
Sort Colors |
Python |
Medium |
Bubble Sort |
75. |
Sort Colors |
Python |
Medium |
Selection Sort |
75. |
Sort Colors |
Python |
Medium |
Insertion Sort |
75. |
Sort Colors |
Python |
Medium |
Quick Sort |
75. |
Sort Colors |
Python |
Medium |
Merge Sort |
78. |
Subsets |
Python |
Medium |
itertools.combinations() |
80. |
Remove Duplicates from Sorted Array II |
Python |
Medium |
|
81. |
Search in Rotated Sorted Array II |
Python |
Medium |
|
82. |
Remove Duplicates from Sorted List II |
Python |
Medium |
Linked List |
83. |
Remove Duplicates from Sorted List |
Python |
Easy |
Linked List |
86. |
Partition List |
Python |
Medium |
Linked List |
88. |
Merge Sorted Array |
Python |
Easy |
Two solutions |
92. |
Reverse Linked List II |
Python |
Medium |
Stack , Linked List |
94. |
Binary Tree Inorder Traversal |
Python |
Medium |
Binary Tree , Recursion |
98. |
Validate Binary Search Tree |
Python |
Medium |
Binary Tree , Recursion |
98. |
Validate Binary Search Tree |
Python |
Medium |
Binary Tree , Recursion , another valid. approach |
100. |
Same Tree |
Python |
Easy |
Binary Tree (preorder), Recursion |
101. |
Symmetric Tree |
Python |
Easy |
BFS , iteratively |
102. |
Binary Tree Level Order Traversal |
Python |
Medium |
BFS , Overcode |
103. |
Binary Tree Zigzag Level Order Traversal |
Python |
Medium |
BFS |
104. |
Maximum Depth of Binary Tree |
Python |
Easy |
Binary Tree , Recursion |
107. |
Binary Tree Level Order Traversal II |
Python |
Easy |
BFS |
110. |
Balanced Binary Tree |
Python |
Easy |
DFS , Recursion |
111. |
Minimum Depth of Binary Tree |
Python |
Easy |
Binary Tree , Recursion |
112. |
Path Sum |
Python |
Easy |
Binary Tree , Recursion |
116. |
Populating Next Right Pointers in Each Node |
Python |
Medium |
BFS |
117. |
Populating Next Right Pointers in Each Node II |
Python |
Medium |
BFS , same as 116 |
118. |
Pascal's Triangle |
Python |
Easy |
|
119. |
Pascal's Triangle II |
Python |
Easy |
|
120. |
Triangle |
Python |
Medium |
|
121. |
Best Time to Buy and Sell Stock |
Python |
Easy |
|
122. |
Best Time to Buy and Sell Stock II |
Python |
Easy |
|
123. |
Best Time to Buy and Sell Stock III |
Python |
Hard |
|
124. |
Binary Tree Maximum Path Sum |
Python |
Hard |
|
125. |
Valid Palindrome |
Python |
Easy |
Two pointers from start & end |
125. |
Valid Palindrome |
Python |
Easy |
Re.findall and left half == rev. right half |
125. |
Valid Palindrome |
Python |
Easy |
Re.sub and s == reversed s |
129. |
Sum Root to Leaf Numbers |
Python |
Medium |
DFS |
134. |
Gas Station |
Python |
Medium |
|
136. |
Single Number |
Python |
Easy |
|
137. |
Single Number II |
Python |
Medium |
Brute Force |
138. |
Copy List with Random Pointer |
Python |
Medium |
Linked List |
139. |
Word Break |
Python |
Medium |
Watched how to complete |
141. |
Linked List Cycle |
Python |
Easy |
Linked List , Brute Force |
141. |
Linked List Cycle |
Python |
Easy |
Linked List , set() |
142. |
Linked List Cycle II |
Python |
Medium |
Linked List , set() |
143. |
Reorder List |
Python |
Medium |
Linked List , Stack |
144. |
Binary Tree Preorder Traversal |
Python |
Medium |
Binary Tree , Recursion |
145. |
Binary Tree Postorder Traversal |
Python |
Hard |
Binary Tree , Recursion |
146. |
LRU Cache |
Python |
Medium |
|
147. |
Insertion Sort List |
Python |
Medium |
Not exactly what asked, Linked List , Binary Search |
148. |
Sort List |
Python |
Medium |
Linked List , Brute Force |
150. |
Evaluate Reverse Polish Notation |
Python |
Medium |
Stack |
152. |
Maximum Product Subarray |
Python |
Medium |
DP |
153. |
Find Minimum in Rotated Sorted Array |
Python |
Medium |
For loop |
153. |
Find Minimum in Rotated Sorted Array |
Python |
Medium |
Binary Search |
154. |
Find Minimum in Rotated Sorted Array II |
Python |
Hard |
For loop |
155. |
Min Stack |
Python |
Easy |
|
160. |
Intersection of Two Linked Lists |
Python |
Easy |
Linked List |
162. |
Find Peak Element |
Python |
Medium |
|
165. |
Compare Version Numbers |
Python |
Medium |
|
167. |
Two Sum II - Input array is sorted |
Python |
Easy |
|
168. |
Excel Sheet Column Title |
Python |
Easy |
|
171. |
Excel Sheet Column Number |
Python |
Easy |
|
172. |
Factorial Trailing Zeroes |
Python |
Easy |
Brute Force |
173. |
Binary Search Tree Iterator |
Python |
Medium |
inorder |
179. |
Largest Number |
Python |
Medium |
Bubble sort |
191. |
Number of 1 Bits |
Python |
Easy |
|
198. |
House Robber |
Python |
Easy |
|
199. |
Binary Tree Right Side View |
Python |
Medium |
BFS |
200. |
Number of Islands |
Python |
Medium |
|
201. |
Bitwise AND of Numbers Range |
Python |
Medium |
|
202. |
Happy Number |
Python |
Easy |
|
203. |
Remove Linked List Elements |
Python |
Easy |
Linked List |
204. |
Count Primes |
Python |
Easy |
|
205. |
Isomorphic Strings |
Python |
Easy |
Dictionary |
206. |
Reverse Linked List |
Python |
Easy |
Linked List , brute force |
206. |
Reverse Linked List |
Python |
Easy |
Linked List |
208. |
Implement Trie (Prefix Tree) |
Python |
Medium |
Trie , 1st time all by myself |
209. |
Minimum Size Subarray Sum |
Python |
Medium |
|
211. |
Add and Search Word - Data structure design |
Python |
Medium |
Need to resolve |
215. |
Kth Largest Element in an Array |
Python |
Medium |
sorted() |
216. |
Combination Sum III |
Python |
Medium |
Backtracking |
217. |
Contains Duplicate |
Python |
Easy |
Dictionary |
219. |
Contains Duplicate II |
Python |
Easy |
Dictionary , enumerate |
220. |
Contains Duplicate III |
Python |
Medium |
Two pointers ? |
221. |
Maximal Square |
Python |
Medium |
|
222. |
Count Complete Tree Nodes |
Python |
Medium |
Recursion |
225. |
Implement Stack using Queues |
Python |
Easy |
List |
226. |
Invert Binary Tree |
Python |
Easy |
Recursion |
227. |
Basic Calculator II |
Python |
Medium |
Queue , Brute Force |
228. |
Summary Ranges |
Python |
Medium |
Two Pointers |
229. |
Majority Element II |
Python |
Medium |
Brute Force |
229. |
Majority Element II |
Python |
Medium |
a bit optimized |
230. |
Kth Smallest Element in a BST |
Python |
Medium |
Recursion , inorder, brute force |
232. |
Implement Queue using Stacks |
Python |
Easy |
List |
234. |
Palindrome Linked List |
Python |
Easy |
Linked List |
237. |
Delete Node in a Linked List |
Python |
Easy |
Linked List |
238. |
Product of Array Except Self |
Python |
Medium |
|
240. |
Search a 2D Matrix II |
Python |
Medium |
Binary Search |
242. |
Valid Anagram |
Python |
Easy |
|
257. |
Binary Tree Paths |
Python |
Easy |
Binary Tree (preorder), Recursion |
258. |
Add Digits |
Python |
Easy |
|
260. |
Single Number III |
Python |
Medium |
Set |
268. |
Missing Number |
Python |
Easy |
|
274. |
H-Index |
Python |
Medium |
|
275. |
H-Index II |
Python |
Medium |
Solution for problem #274 worked fine |
283. |
Move Zeroes |
Python |
Easy |
|
284. |
Peeking Iterator |
Python |
Medium |
|
289. |
Game of Life |
Python |
Medium |
|
290. |
Word Pattern |
Python |
Easy |
Dictionary , enumerate |
295. |
Find Median from Data Stream |
Python |
Hard |
Brute Force |
295. |
Find Median from Data Stream |
Python |
Hard |
Binary Search |
297. |
Serialize and Deserialize Binary Tree |
Python |
Hard |
BFS |
299. |
Bulls and Cows |
Python |
Easy |
|
304. |
Range Sum Query 2D - Immutable |
Python |
Medium |
Brute force |
304. |
Range Sum Query 2D - Immutable |
Python |
Medium |
A bit optimized but still brute force |
326. |
Power of Three |
Python |
Easy |
while |
328. |
Odd Even Linked List |
Python |
Medium |
Linked List |
329. |
Longest Increasing Path in a Matrix |
Python |
Hard |
DFS , LRU_cache , Brute Force |
334. |
Increasing Triplet Subsequence |
Python |
Medium |
Brute Force |
341. |
Flatten Nested List Iterator |
Python |
Medium |
|
342. |
Power of Four |
Python |
Easy |
Brute Force |
342. |
Power of Four |
Python |
Easy |
Bitwise |
344. |
Reverse String |
Python |
Easy |
|
345. |
Reverse Vowels of a String |
Python |
Easy |
String , in-place, slow |
345. |
Reverse Vowels of a String |
Python |
Easy |
List , fast, ~x4 |
347. |
Top K Frequent Elements |
Python |
Medium |
Hash Table |
355. |
Design Twitter |
Python |
Medium |
May be improved with collections |
376. |
Wiggle Subsequence |
Python |
Medium |
|
378. |
Kth Smallest Element in a Sorted Matrix |
Python |
Medium |
Converted matrix into list |
380. |
Insert Delete GetRandom O(1) |
Python |
Medium |
not O(1), Brute force |
381. |
Insert Delete GetRandom O(1) - Duplicates allowed |
Python |
Hard |
not O(1), Brute force |
382. |
Linked List Random Node |
Python |
Medium |
random.choice() |
384. |
Shuffle an Array |
Python |
Medium |
random.sample() |
387. |
First Unique Character in a String |
Python |
Easy |
Brute Force |
387. |
First Unique Character in a String |
Python |
Easy |
Dictionary , enumerate |
389. |
Find the Difference |
Python |
Easy |
set , .count() |
389. |
Find the Difference |
Python |
Easy |
.replace() |
392. |
Is Subsequence |
Python |
Easy |
|
394. |
Decode String |
Python |
Medium |
Stack |
395. |
Longest Substring with At Least K Repeating Characters |
Python |
Medium |
collections , Recursion |
398. |
Random Pick Index |
Python |
Medium |
random.choice() |
399. |
Evaluate Division |
Python |
Medium |
God bless youtube |
402. |
Remove K Digits |
Python |
Medium |
Stack |
404. |
Sum of Left Leaves |
Python |
Easy |
Recursion , preorder |
409. |
Longest Palindrome |
Python |
Easy |
|
412. |
Fizz Buzz |
Python |
Easy |
|
421. |
Maximum XOR of Two Numbers in an Array |
Python |
Medium |
googled soln |
423. |
Reconstruct Original Digits from English |
Python |
Medium |
|
429. |
N-ary Tree Level Order Traversal |
Python |
Medium |
BFS |
432. |
All O`one Data Structure |
Python |
Hard |
Dictionary as Data Structure |
435. |
Non-overlapping Intervals |
Python |
Medium |
lambda |
436. |
Find Right Interval |
Python |
Medium |
Brute Force |
437. |
Path Sum III |
Python |
Medium |
DFS |
441. |
Arranging Coins |
Python |
Easy |
Iteratively |
442. |
Find All Duplicates in an Array |
Python |
Medium |
set() |
445. |
Add Two Numbers II |
Python |
Medium |
converted to int and back to Linked List |
449. |
Serialize and Deserialize BST |
Python |
Medium |
Complicated solution - resolve |
450. |
Delete Node in a BST |
Python |
Medium |
Binary Search Tree , Recursion |
451. |
Sort Characters By Frequency |
Python |
Medium |
Surprisingly fast solution |
452. |
Minimum Number of Arrows to Burst Balloons |
Python |
Medium |
|
454. |
4Sum II |
Python |
Medium |
Dictionary |
456. |
132 Pattern |
Python |
Medium |
Brute Force |
458. |
Poor Pigs |
Python |
Hard |
math |
459. |
Repeated Substring Pattern |
Python |
Easy |
|
468. |
Validate IP Address |
Python |
Medium |
|
470. |
Implement Rand10() Using Rand7() |
Python |
Medium |
'Invented the wheel' |
476. |
Number Complement |
Python |
Easy |
|
478. |
Generate Random Point in a Circle |
Python |
Medium |
|
495. |
Teemo Attacking |
Python |
Medium |
|
496. |
Next Greater Element I |
Python |
Easy |
Brute force - resolve |
497. |
Random Point in Non-overlapping Rectangles |
Python |
Medium |
Random , Bisect |
498. |
Diagonal Traverse |
Python |
Medium |
Used theory from GfG.com |
500. |
Keyboard Row |
Python |
Easy |
Dictionary |
501. |
Find Mode in Binary Search Tree |
Python |
Easy |
Recursion |
503. |
Next Greater Element II |
Python |
Medium |
Brute Force |
509. |
Fibonacci Number |
Python |
Easy |
List |
509. |
Fibonacci Number |
Python |
Easy |
Dictionary |
509. |
Fibonacci Number |
Python |
Easy |
Used two variables n1 & n2 |
513. |
Find Bottom Left Tree Value |
Python |
Medium |
BFS |
515. |
Find Largest Value in Each Tree Row |
Python |
Medium |
BFS |
520. |
Detect Capital |
Python |
Easy |
Built-in functions |
524. |
Longest Word in Dictionary through Deleting |
Python |
Medium |
|
525. |
Contiguous Array |
Python |
Medium |
|
526. |
Beautiful Arrangement |
Python |
Medium |
DFS , brute force |
530. |
Minimum Absolute Difference in BST |
Python |
Easy |
Bad solution - resolve |
532. |
K-diff Pairs in an Array |
Python |
Medium |
Brute force |
535. |
Encode and Decode TinyURL |
Python |
Medium |
Dictionary as db, random generated url |
538. |
Convert BST to Greater Tree |
Python |
Easy |
DFS , recursion |
540. |
Single Element in a Sorted Array |
Python |
Medium |
Binary Search |
543. |
Diameter of Binary Tree |
Python |
Easy |
|
554. |
Brick Wall |
Python |
Medium |
Hash Table |
556. |
Next Greater Element III |
Python |
Medium |
|
559. |
Maximum Depth of N-ary Tree |
Python |
Easy |
BFS |
560. |
Subarray Sum Equals K |
Python |
Medium |
|
563. |
Binary Tree Tilt |
Python |
Easy |
Binary Tree , postorder , overcode |
575. |
Distribute Candies |
Python |
Easy |
|
581. |
Shortest Unsorted Continuous Subarray |
Python |
Medium |
|
589. |
N-ary Tree Preorder Traversal |
Python |
Easy |
Recursion |
590. |
N-ary Tree Postorder Traversal |
Python |
Easy |
Recursion |
593. |
Valid Square |
Python |
Medium |
|
594. |
Longest Harmonious Subsequence |
Python |
Easy |
defaultdict |
594. |
Longest Harmonious Subsequence |
Python |
Easy |
Counter |
599. |
Minimum Index Sum of Two Lists |
Python |
Easy |
Dictionary , enumerate |
605. |
Can Place Flowers |
Python |
Easy |
simple counter |
609. |
Find Duplicate File in System |
Python |
Medium |
Dictionary , nested for loop , list comprehension |
622. |
Design Circular Queue |
Python |
Medium |
Implement through list (first time) |
623. |
Add One Row to Tree |
Python |
Medium |
BFS |
637. |
Average of Levels in Binary Tree |
Python |
Easy |
Binary Tree , Recursion |
641. |
Design Circular Deque |
Python |
Medium |
Need to resolve without use of builtin functions (first time) |
645. |
Set Mismatch |
Python |
Easy |
collections.Counter |
647. |
Palindromic Substrings |
Python |
Medium |
|
653. |
Two Sum IV - Input is a BST |
Python |
Easy |
Brute Force - resolve |
654. |
Maximum Binary Tree |
Python |
Medium |
DFS , Recursion |
657. |
Robot Return to Origin |
Python |
Easy |
Dictionary |
658. |
Find K Closest Elements |
Python |
Medium |
Binary Search |
665. |
Non-decreasing Array |
Python |
Easy |
Brute Force |
667. |
Beautiful Arrangement II |
Python |
Medium |
|
671. |
Second Minimum Node In a Binary Tree |
Python |
Easy |
DFS , Recursion |
674. |
Longest Continuous Increasing Subsequence |
Python |
Easy |
simple counter |
677. |
Map Sum Pairs |
Python |
Medium |
Trie |
678. |
Valid Parenthesis String |
Python |
Medium |
|
682. |
Baseball Game |
Python |
Easy |
|
690. |
Employee Importance |
Python |
Easy |
BFS |
696. |
Count Binary Substrings |
Python |
Easy |
|
700. |
Search in a Binary Search Tree |
Python |
Easy |
Binary Search Tree , Recursion |
701. |
Insert into a Binary Search Tree |
Python |
Medium |
Binary Search Tree , Recursion |
703. |
Kth Largest Element in a Stream |
Python |
Easy |
brute force |
705. |
Design HashSet |
Python |
Easy |
list as a set |
706. |
Design HashMap |
Python |
Easy |
list |
707. |
Design Linked List |
Python |
Medium |
Linked List , first time |
709. |
To Lower Case |
Python |
Easy |
Two solutions. 1st w. in place changes, 2nd saves in var |
713. |
Subarray Product Less Than K |
Python |
Medium |
Two pointers |
720. |
Longest Word in Dictionary |
Python |
Easy |
Trie |
722. |
Remove Comments |
Python |
Medium |
String |
728. |
Self Dividing Numbers |
Python |
Easy |
Math |
735. |
Asteroid Collision |
Python |
Medium |
Stack |
744. |
Find Smallest Letter Greater Than Target |
Python |
Easy |
Binary Search |
754. |
Reach a Number |
Python |
Medium |
Math |
763. |
Partition Labels |
Python |
Medium |
Brute Force - resolve |
771. |
Jewels and Stones |
Python |
Easy |
while loop , for loop and list comprehension |
775. |
Global and Local Inversions |
Python |
Medium |
|
785. |
Is Graph Bipartite? |
Python |
Medium |
Iteratively BFS , stack , XOR |
804. |
Unique Morse Code Words |
Python |
Easy |
Dictionary |
807. |
Max Increase to Keep City Skyline |
Python |
Medium |
|
811. |
Subdomain Visit Count |
Python |
Easy |
Dictionary |
817. |
Linked List Components |
Python |
Medium |
Set |
817. |
Linked List Components |
Python |
Medium |
List , 35 times slower |
820. |
Short Encoding of Words |
Python |
Medium |
Brute Force |
821. |
Shortest Distance to a Character |
Python |
Easy |
overcode |
824. |
Goat Latin |
Python |
Easy |
|
832. |
Flipping an Image |
Python |
Easy |
|
832. |
Flipping an Image |
Python |
Easy |
.reverse() |
835. |
Image Overlap |
Python |
Medium |
Brute Force |
841. |
Keys and Rooms |
Python |
Medium |
BFS |
844. |
Backspace String Compare |
Python |
Easy |
|
845. |
Longest Mountain in Array |
Python |
Medium |
one pass |
849. |
Maximize Distance to Closest Person |
Python |
Medium |
|
852. |
Peak Index in a Mountain Array |
Python |
Easy |
List comprehension |
852. |
Peak Index in a Mountain Array |
Python |
Easy |
Set |
858. |
Mirror Reflection |
Python |
Medium |
|
859. |
Buddy Strings |
Python |
Easy |
Brute Force |
865. |
Smallest Subtree with all the Deepest Nodes |
Python |
Medium |
DFS , Recursion |
869. |
Reordered Power of 2 |
Python |
Medium |
int to string |
872. |
Leaf-Similar Trees |
Python |
Easy |
Recursion |
876. |
Middle of the Linked List |
Python |
Easy |
|
880. |
Decoded String at Index |
Python |
Medium |
|
881. |
Boats to Save People |
Python |
Medium |
Two Pointers |
884. |
Uncommon Words from Two Sentences |
Python |
Easy |
simple counter |
890. |
Find and Replace Pattern |
Python |
Medium |
Dictionary |
895. |
Maximum Frequency Stack |
Python |
Hard |
|
896. |
Monotonic Array |
Python |
Easy |
|
897. |
Increasing Order Search Tree |
Python |
Easy |
DFS , iteratively |
900. |
RLE Iterator |
Python |
Medium |
|
905. |
Sort Array By Parity |
Python |
Easy |
List |
908. |
Smallest Range I |
Python |
Easy |
|
910. |
Smallest Range II |
Python |
Medium |
|
911. |
Online Election |
Python |
Medium |
Binary Search |
912. |
Sort an Array |
Python |
Medium |
sorted() |
916. |
Word Subsets |
Python |
Medium |
collections.Counter , Dictionary |
922. |
Sort Array By Parity II |
Python |
Easy |
Dictionary |
922. |
Sort Array By Parity II |
Python |
Easy |
List |
922. |
Sort Array By Parity II |
Python |
Easy |
Two Pointers |
923. |
3Sum With Multiplicity |
Python |
Medium |
collections.Counter |
929. |
Unique Email Addresses |
Python |
Easy |
|
933. |
Number of Recent Calls |
Python |
Easy |
Binary Search and rewrite list |
933. |
Number of Recent Calls |
Python |
Easy |
while and rewrite list |
933. |
Number of Recent Calls |
Python |
Easy |
while and .pop() |
938. |
Range Sum of BST |
Python |
Easy |
Binary Search Tree |
938. |
Range Sum of BST |
Python |
Easy |
Binary Search Tree , Optimized solution |
941. |
Valid Mountain Array |
Python |
Easy |
|
946. |
Validate Stack Sequences |
Python |
Medium |
Stack |
949. |
Largest Time for Given Digits |
Python |
Easy |
Itertools |
952. |
Largest Component Size by Common Factor |
Python |
Hard |
Googled soln |
953. |
Verifying an Alien Dictionary |
Python |
Easy |
|
961. |
N-Repeated Element in Size 2N Array |
Python |
Easy |
Brute Force |
961. |
N-Repeated Element in Size 2N Array |
Python |
Easy |
Dictionary , a bit optimized |
965. |
Univalued Binary Tree |
Python |
Easy |
Binary Tree , Recursion |
966. |
Vowel Spellchecker |
Python |
Medium |
Dictionary |
967. |
Numbers With Same Consecutive Differences |
Python |
Medium |
DFS |
969. |
Pancake Sorting |
Python |
Medium |
sort |
970. |
Powerful Integers |
Python |
Medium |
nested for loops |
977. |
Squares of a Sorted Array |
Python |
Easy |
|
980. |
Unique Paths III |
Python |
Hard |
"googled soln", optimised |
981. |
Time Based Key-Value Store |
Python |
Medium |
Binary Search |
983. |
Minimum Cost For Tickets |
Python |
Medium |
Googled soln |
987. |
Vertical Order Traversal of a Binary Tree |
Python |
Medium |
DFS |
989. |
Add to Array-Form of Integer |
Python |
Easy |
list ->int ->list |
991. |
Broken Calculator |
Python |
Medium |
BFS |
993. |
Cousins in Binary Tree |
Python |
Easy |
BFS , iteratively |
994. |
Rotting Oranges |
Python |
Medium |
DFS |
999. |
Available Captures for Rook |
Python |
Easy |
|
1002. |
Find Common Characters |
Python |
Easy |
Dictionary |
1009. |
Complement of Base 10 Integer |
Python |
Easy |
|
1010. |
Pairs of Songs With Total Durations Divisible by 60 |
Python |
Medium |
|
1015. |
Smallest Integer Divisible by K |
Python |
Medium |
counting lenght, Brute Force |
1019. |
Next Greater Node In Linked List |
Python |
Medium |
|
1021. |
Remove Outermost Parentheses |
Python |
Easy |
Overcode |
1022. |
Sum of Root To Leaf Binary Numbers |
Python |
Easy |
DFS , Recursion |
1025. |
Divisor Game |
Python |
Easy |
|
1026. |
Maximum Difference Between Node and Ancestor |
Python |
Medium |
BFS , iteratively |
1032. |
Stream of Characters |
Python |
Hard |
Trie |
1038. |
Binary Search Tree to Greater Sum Tree |
Python |
Medium |
DFS , recursion |
1041. |
Robot Bounded In Circle |
Python |
Medium |
Dictionary |
1046. |
Last Stone Weight |
Python |
Easy |
|
1047. |
Remove All Adjacent Duplicates In String |
Python |
Easy |
Brute force - resolve |
1079. |
Letter Tile Possibilities |
Python |
Medium |
itertools, permutations |
1091. |
Shortest Path in Binary Matrix |
Python |
Medium |
BFS , grid/matrix |
1094. |
Car Pooling |
Python |
Medium |
|
1095. |
Find in Mountain Array |
Python |
Hard |
Binary Search |
1103. |
Distribute Candies to People |
Python |
Easy |
|
1108. |
Defanging an IP Address |
Python |
Easy |
.replace() |
1108. |
Defanging an IP Address |
Python |
Easy |
re.sub |
1108. |
Defanging an IP Address |
Python |
Easy |
.join() |
1122. |
Relative Sort Array |
Python |
Easy |
|
1123. |
Lowest Common Ancestor of Deepest Leaves |
Python |
Medium |
DFS , recursion |
1143. |
Longest Common Subsequence |
Python |
Medium |
2D Array |
1143. |
Longest Common Subsequence |
Python |
Medium |
Recursion , Time Limit Exceeded |
1160. |
Find Words That Can Be Formed by Characters |
Python |
Easy |
Dictionary |
1161. |
Maximum Level Sum of a Binary Tree |
Python |
Medium |
BFS |
1169. |
Invalid Transactions |
Python |
Medium |
Ugly brute force |
1171. |
Remove Zero Sum Consecutive Nodes from Linked List |
Python |
Medium |
Brute Force - resolve |
1189. |
Maximum Number of Balloons |
Python |
Easy |
simple counter |
1200. |
Minimum Absolute Difference |
Python |
Easy |
Dictionary |
1207. |
Unique Number of Occurrences |
Python |
Easy |
Dictionary |
1217. |
Minimum Cost to Move Chips to The Same Position |
Python |
Easy |
simple counter |
1221. |
Split a String in Balanced Strings |
Python |
Easy |
Stack |
1227. |
Airplane Seat Assignment Probability |
Python |
Medium |
|
1237. |
Find Positive Integer Solution for a Given Equation |
Python |
Easy |
Binary Search |
1252. |
Cells with Odd Values in a Matrix |
Python |
Easy |
|
1260. |
Shift 2D Grid |
Python |
Easy |
array |
1261. |
Find Elements in a Contaminated Binary Tree |
Python |
Medium |
DFS , iteratively |
1266. |
Minimum Time Visiting All Points |
Python |
Easy |
simple counter |
1282. |
Group the People Given the Group Size They Belong To |
Python |
Medium |
|
1283. |
Find the Smallest Divisor Given a Threshold |
Python |
Medium |
Binary Search |
1286. |
Iterator for Combination |
Python |
Medium |
Itertools |
1287. |
Element Appearing More Than 25% In Sorted Array |
Python |
Easy |
for loop |
1287. |
Element Appearing More Than 25% In Sorted Array |
Python |
Easy |
Binary Search |
1288. |
Remove Covered Intervals |
Python |
Medium |
Brute force |
1290. |
Convert Binary Number in a Linked List to Integer |
Python |
Easy |
|
1291. |
Sequential Digits |
Python |
Medium |
String , can be solved with int |
1299. |
Replace Elements with Greatest Element on Right Side |
Python |
Easy |
|
1302. |
Deepest Leaves Sum |
Python |
Medium |
DFS |
1304. |
Find N Unique Integers Sum up to Zero |
Python |
Easy |
|
1305. |
All Elements in Two Binary Search Trees |
Python |
Medium |
BFS , iteratively |
1306. |
Jump Game III |
Python |
Medium |
BFS , iteratively |
1309. |
Decrypt String from Alphabet to Integer Mapping |
Python |
Easy |
|
1311. |
Get Watched Videos by Your Friends |
Python |
Medium |
BFS , iteratively |
1313. |
Decompress Run-Length Encoded List |
Python |
Easy |
|
1315. |
Sum of Nodes with Even-Valued Grandparent |
Python |
Medium |
DFS , recursion |
1323. |
Maximum 69 Number |
Python |
Easy |
|
1325. |
Delete Leaves With a Given Value |
Python |
Medium |
DFS , recursion |
1329. |
Sort the Matrix Diagonally |
Python |
Medium |
List |
1331. |
Rank Transform of an Array |
Python |
Easy |
Enumerate |
1332. |
Remove Palindromic Subsequences |
Python |
Easy |
Bad problem question |
1337. |
The K Weakest Rows in a Matrix |
Python |
Easy |
|
1338. |
Reduce Array Size to The Half |
Python |
Medium |
Dictionary , Enumerate |
1342. |
Number of Steps to Reduce a Number to Zero |
Python |
Easy |
while loop |
1345. |
Jump Game IV |
Python |
Hard |
BFS , iteratively |
1347. |
Minimum Number of Steps to Make Two Strings Anagram |
Python |
Medium |
|
1348. |
Tweet Counts Per Frequency |
Python |
Medium |
Too slow, need to resolve it |
1351. |
Count Negative Numbers in a Sorted Matrix |
Python |
Easy |
Binary Search |
1351. |
Count Negative Numbers in a Sorted Matrix |
Python |
Easy |
nested for loop |
1351. |
Count Negative Numbers in a Sorted Matrix |
Python |
Easy |
nested for loop with a break |
1352. |
Product of the Last K Numbers |
Python |
Medium |
Brute Force |
1352. |
Product of the Last K Numbers |
Python |
Medium |
Optimized, but overcode |
1352. |
Product of the Last K Numbers |
Python |
Medium |
|
1357. |
Apply Discount Every n Orders |
Python |
Medium |
Brute Force |
1357. |
Apply Discount Every n Orders |
Python |
Medium |
Dictionary |
1361. |
Validate Binary Tree Nodes |
Python |
Medium |
BFS , iteratively |
1365. |
How Many Numbers Are Smaller Than the Current Number |
Python |
Easy |
List comprehension |
1367. |
Linked List in Binary Tree |
Python |
Medium |
DFS , Linked List , Binary Tree |
1370. |
Increasing Decreasing String |
Python |
Easy |
|
1374. |
Generate a String With Characters That Have Odd Counts |
Python |
Easy |
|
1379. |
Find a Corresponding Node of a Binary Tree in a Clone of That Tree |
Python |
Medium |
Stack , iteratively |
1379. |
Find a Corresponding Node of a Binary Tree in a Clone of That Tree |
Python |
Medium |
DFS , recursion |
1380. |
Lucky Numbers in a Matrix |
Python |
Easy |
Nested for loops |
1381. |
Design a Stack With Increment Operation |
Python |
Medium |
List as Stack |
1387. |
Sort Integers by The Power Value |
Python |
Medium |
|
1389. |
Create Target Array in the Given Order |
Python |
Easy |
enumerate , insert |
1395. |
Count Number of Teams |
Python |
Medium |
Brute Force |
1396. |
Design Underground System |
Python |
Medium |
Dictionary |
1403. |
Minimum Subsequence in Non-Increasing Order |
Python |
Easy |
List |
1403. |
Minimum Subsequence in Non-Increasing Order |
Python |
Easy |
sum (int ) comparison |
1409. |
Queries on a Permutation With Key |
Python |
Medium |
|
1410. |
HTML Entity Parser |
Python |
Medium |
Re.sub |
1414. |
Find the Minimum Number of Fibonacci Numbers Whose Sum Is K |
Python |
Medium |
Greedy |
1423. |
Maximum Points You Can Obtain from Cards |
Python |
Medium |
Sliding Window |
1426. |
Counting Elements |
Python |
Easy |
|
1427. |
Perform String Shifts |
Python |
Easy |
|
1428. |
Leftmost Column with at Least a One |
Python |
Medium |
|
1429. |
First Unique Number |
Python |
Medium |
|
1430. |
Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree |
Python |
Medium |
|
1431. |
Kids With the Greatest Number of Candies |
Python |
Easy |
List comprehension |
1436. |
Destination City |
Python |
Easy |
Dictionary |
1436. |
Destination City |
Python |
Easy |
Set |
1437. |
Check If All 1's Are at Least Length K Places Away |
Python |
Medium |
|
1441. |
Build an Array With Stack Operations |
Python |
Easy |
List |
1446. |
Consecutive Characters |
Python |
Easy |
Two pointers |
1448. |
Count Good Nodes in Binary Tree |
Python |
Medium |
DFS , Binary Tree |
1448. |
Count Good Nodes in Binary Tree |
Python |
Medium |
optimized DFS , Binary Tree |
1450. |
Number of Students Doing Homework at a Given Time |
Python |
Easy |
Enumerate |
1455. |
Check If a Word Occurs As a Prefix of Any Word in a Sentence |
Python |
Easy |
Enumerate |
1457. |
Pseudo-Palindromic Paths in a Binary Tree |
Python |
Medium |
DFS , recursion |
1460. |
Make Two Arrays Equal by Reversing Sub-arrays |
Python |
Easy |
|
1461. |
Check If a String Contains All Binary Codes of Size K |
Python |
Medium |
Brute Force |
1463. |
Cherry Pickup II |
Python |
Hard |
DFS , lfu cache |
1464. |
Maximum Product of Two Elements in an Array |
Python |
Easy |
|
1470. |
Shuffle the Array |
Python |
Easy |
Zip |
1472. |
Design Browser History |
Python |
Medium |
Doubly Linked List |
1472. |
Design Browser History |
Python |
Medium |
Dictionary |
1475. |
Final Prices With a Special Discount in a Shop |
Python |
Easy |
kinda Brute force |
1476. |
Subrectangle Queries |
Python |
Medium |
nested for loop |
1480. |
Running Sum of 1d Array |
Python |
Easy |
|
1480. |
Running Sum of 1d Array |
Python |
Easy |
List comprehension |
1486. |
XOR Operation in an Array |
Python |
Easy |
|
1487. |
Making File Names Unique |
Python |
Medium |
|
1491. |
Average Salary Excluding the Minimum and Maximum Salary |
Python |
Easy |
|
1492. |
The kth Factor of n |
Python |
Medium |
|
1496. |
Path Crossing |
Python |
Easy |
|
1502. |
Can Make Arithmetic Progression From Sequence |
Python |
Easy |
|
1507. |
Reformat Date |
Python |
Easy |
List |
1507. |
Reformat Date |
Python |
Easy |
Without conberting String into List |
1512. |
Number of Good Pairs |
Python |
Easy |
Dictionary |
1512. |
Number of Good Pairs |
Python |
Easy |
Nested for loops |
1518. |
Water Bottles |
Python |
Easy |
While loop |
1523. |
Count Odd Numbers in an Interval Range |
Python |
Easy |
|
1528. |
Shuffle String |
Python |
Easy |
List |
1528. |
Shuffle String |
Python |
Easy |
String |
1534. |
Count Good Triplets |
Python |
Easy |
|
1539. |
Kth Missing Positive Number |
Python |
Easy |
List |
1544. |
Make The String Great |
Python |
Easy |
Stack |
1544. |
Make The String Great |
Python |
Easy |
String in-place |
1545. |
Find Kth Bit in Nth Binary String |
Python |
Medium |
Brute Force |
1550. |
Three Consecutive Odds |
Python |
Easy |
simple counter |
1551. |
Minimum Operations to Make Array Equal |
Python |
Medium |
|
1556. |
Thousand Separator |
Python |
Easy |
String , List |
1557. |
Minimum Number of Vertices to Reach All Nodes |
Python |
Medium |
Set , kinda Brute Force |
1561. |
Maximum Number of Coins You Can Get |
Python |
Medium |
|
1566. |
Detect Pattern of Length M Repeated K or More Times |
Python |
Easy |
|
1567. |
Maximum Length of Subarray With Positive Product |
Python |
Medium |
kinda Brute force |
1572. |
Matrix Diagonal Sum |
Python |
Easy |
|
1576. |
Replace All ?'s to Avoid Consecutive Repeating Characters |
Python |
Easy |
Fast but awful soln. |
1582. |
Special Positions in a Binary Matrix |
Python |
Easy |
|
1588. |
Sum of All Odd Length Subarrays |
Python |
Easy |
Two Pointers |
1592. |
Rearrange Spaces Between Words |
Python |
Easy |
|
1598. |
Crawler Log Folder |
Python |
Easy |
|
1603. |
Design Parking System |
Python |
Easy |
Dictionary |
1609. |
Even Odd Tree |
Python |
Medium |
BFS |
1614. |
Maximum Nesting Depth of the Parentheses |
Python |
Easy |
|
1619. |
Mean of Array After Removing Some Elements |
Python |
Easy |
|
1624. |
Largest Substring Between Two Equal Characters |
Python |
Easy |
|
1629. |
Slowest Key |
Python |
Easy |
|
1630. |
Arithmetic Subarrays |
Python |
Medium |
|
1631. |
Path With Minimum Effort |
Python |
Medium |
DFS , Binary Search , Brute force |
1636. |
Sort Array by Increasing Frequency |
Python |
Easy |
complicated counter |
1637. |
Widest Vertical Area Between Two Points Containing No Points |
Python |
Medium |
|
1640. |
Check Array Formation Through Concatenation |
Python |
Easy |
|
1641. |
Count Sorted Vowel Strings |
Python |
Medium |
itertools |
1646. |
Get Maximum in Generated Array |
Python |
Easy |
while |
1646. |
Get Maximum in Generated Array |
Python |
Easy |
for |
1652. |
Defuse the Bomb |
Python |
Easy |
|
1656. |
Design an Ordered Stream |
Python |
Easy |
list |
1657. |
Determine if Two Strings Are Close |
Python |
Medium |
collections.Counter |
1658. |
Minimum Operations to Reduce X to Zero |
Python |
Medium |
|
1662. |
Check If Two String Arrays are Equivalent |
Python |
Easy |
.join() |
1663. |
Smallest String With A Given Numeric Value |
Python |
Medium |
|
1668. |
Maximum Repeating Substring |
Python |
Easy |
|
1669. |
Merge In Between Linked Lists |
Python |
Medium |
Linked List |
1670. |
Design Front Middle Back Queue |
Python |
Medium |
List |
1672. |
Richest Customer Wealth |
Python |
Easy |
|
1673. |
Find the Most Competitive Subsequence |
Python |
Medium |
Stack |
1678. |
Goal Parser Interpretation |
Python |
Easy |
.replace() |
1678. |
Goal Parser Interpretation |
Python |
Easy |
iteratively |
1679. |
Max Number of K-Sum Pairs |
Python |
Medium |
collections , Counter |
1680. |
Concatenation of Consecutive Binary Numbers |
Python |
Medium |
|
1684. |
Count the Number of Consistent Strings |
Python |
Easy |
|
1685. |
Sum of Absolute Differences in a Sorted Array |
Python |
Medium |
|
1688. |
Count of Matches in Tournament |
Python |
Easy |
simple counter |
1689. |
Partitioning Into Minimum Number Of Deci-Binary Numbers |
Python |
Medium |
max() |
1694. |
Reformat Phone Number |
Python |
Easy |
|
1695. |
Maximum Erasure Value |
Python |
Medium |
|
1700. |
Number of Students Unable to Eat Lunch |
Python |
Easy |
simple counter |
1704. |
Determine if String Halves Are Alike |
Python |
Easy |
simple counter |
1710. |
Maximum Units on a Truck |
Python |
Easy |
Dictionary |
1716. |
Calculate Money in Leetcode Bank |
Python |
Easy |
|
1720. |
Decode XORed Array |
Python |
Easy |
|
1721. |
Swapping Nodes in a Linked List |
Python |
Medium |
Linked List , Queue |
1725. |
Number Of Rectangles That Can Form The Largest Square |
Python |
Easy |
collections.defaultdict |
1732. |
Find the Highest Altitude |
Python |
Easy |
|
1748. |
Sum of Unique Elements |
Python |
Easy |
collections.Counter |
1752. |
Check if Array Is Sorted and Rotated |
Python |
Easy |
|
1773. |
Count Items Matching a Rule |
Python |
Easy |
|
1790. |
Check if One String Swap Can Make Strings Equal |
Python |
Easy |
|
1791. |
Find Center of Star Graph |
Python |
Medium |
|
1796. |
Second Largest Digit in a String |
Python |
Easy |
|
1800. |
Maximum Ascending Subarray Sum |
Python |
Easy |
|
1805. |
Number of Different Integers in a String |
Python |
Easy |
|
1812. |
Determine Color of a Chessboard Square |
Python |
Easy |
|
1816. |
Truncate Sentence |
Python |
Easy |
|