Leetcode Solutions¶

Algorithmic problem solutions with visual animations.

Each problem includes: - Problem description and difficulty level - Solution code (Go, Java, Python) - Time and space complexity analysis - Visual animation

#	Problem	Difficulty
1	Two Sum	Easy
2	Add Two Numbers	Medium
3	Longest Substring Without Repeating Characters	Medium
4	Median of Two Sorted Arrays	Hard
5	Longest Palindromic Substring	Medium
6	Zigzag Conversion	Medium
7	Reverse Integer	Medium
8	String to Integer (atoi)	Medium
9	Palindrome Number	Easy
10	Regular Expression Matching	Hard
11	Container With Most Water	Medium
12	Integer to Roman	Medium
13	Roman to Integer	Easy
14	Longest Common Prefix	Easy
15	3Sum	Medium
16	3Sum Closest	Medium
17	Letter Combinations of a Phone Number	Medium
18	4Sum	Medium
19	Remove Nth Node From End of List	Medium
20	Valid Parentheses	Easy
21	Merge Two Sorted Lists	Easy
22	Generate Parentheses	Medium
23	Merge k Sorted Lists	Hard
24	Swap Nodes in Pairs	Medium
25	Reverse Nodes in k-Group	Hard
26	Remove Duplicates from Sorted Array	Easy
27	Remove Element	Easy
28	Find the Index of the First Occurrence in a String	Easy
29	Divide Two Integers	Medium
30	Substring with Concatenation of All Words	Hard
31	Next Permutation	Medium
32	Longest Valid Parentheses	Hard
33	Search in Rotated Sorted Array	Medium
34	Find First and Last Position of Element in Sorted Array	Medium
35	Search Insert Position	Easy
36	Valid Sudoku	Medium
37	Sudoku Solver	Hard
38	Count and Say	Medium
39	Combination Sum	Medium
40	Combination Sum II	Medium
41	First Missing Positive	Hard
42	Trapping Rain Water	Hard
43	Multiply Strings	Medium
44	Wildcard Matching	Hard
45	Jump Game II	Medium
46	Permutations	Medium
47	Permutations II	Medium
48	Rotate Image	Medium
49	Group Anagrams	Medium
50	Pow(x, n)	Medium
51	N-Queens	Hard
52	N-Queens II	Hard
53	Maximum Subarray	Medium
54	Spiral Matrix	Medium
55	Jump Game	Medium
56	Merge Intervals	Medium
57	Insert Interval	Medium
58	Length of Last Word	Easy
59	Spiral Matrix II	Medium
60	Permutation Sequence	Hard
61	Rotate List	Medium
62	Unique Paths	Medium
63	Unique Paths II	Medium
64	Minimum Path Sum	Medium
65	Valid Number	Hard
66	Plus One	Easy
67	Add Binary	Easy
68	Text Justification	Hard
69	Sqrt(x)	Easy
70	Climbing Stairs	Easy
71	Simplify Path	Medium
72	Edit Distance	Hard
73	Set Matrix Zeroes	Medium
74	Search a 2D Matrix	Medium
75	Sort Colors	Medium
76	Minimum Window Substring	Hard
77	Combinations	Medium
78	Subsets	Medium
79	Word Search	Medium
80	Remove Duplicates from Sorted Array II	Medium
81	Search in Rotated Sorted Array II	Medium
82	Remove Duplicates from Sorted List II	Medium
83	Remove Duplicates from Sorted List	Easy
84	Largest Rectangle in Histogram	Hard
85	Maximal Rectangle	Hard
86	Partition List	Medium
87	Scramble String	Hard
88	Merge Sorted Array	Easy
89	Gray Code	Medium
90	Subsets II	Medium
91	Decode Ways	Medium
92	Reverse Linked List II	Medium
93	Restore IP Addresses	Medium
94	Binary Tree Inorder Traversal	Easy
95	Unique Binary Search Trees II	Medium
96	Unique Binary Search Trees	Medium
97	Interleaving String	Medium
98	Validate Binary Search Tree	Medium
99	Recover Binary Search Tree	Medium
100	Same Tree	Easy