更多内容敬请期待。解法是否最优不能保证，但OJ肯定是能过的。
1: Two Sum
2: Median of Two Sorted Arrays
3: Longest Substring Without Repeating Characters
4: Add Two Numbers
5: Longest Palindromic Substring
6: ZigZag Conversion
7: Reverse Integer
8: String to Integer (atoi)
9: Palindrome Number
10: Regular Expression Matching
11: Container With Most Water
12: Integer to Roman
13: Roman to Integer
14: Longest Common Prefix
15: 3Sum
16: 3Sum Closest
17: Letter Combinations of a Phone Number
18: 4Sum
18: Remove Nth Node From End of List
20: Valid Parentheses
21: Generate Parentheses
22: Merge k Sorted Lists
23: Swap Nodes in Pairs
24: Reverse Nodes in k-Group
25: Remove Element
26: Remove Duplicates from Sorted Array
27: Implement strStr()
28: Divide Two Integers
29: Substring with Concatenation of All Words
30: Next Permutation
31: Longest Valid Parentheses
32: Search in Rotated Sorted Array
33: Search for a Range
34: Search Insert Position
35: Valid Sudoku
36: Sudoku Solver
37: Count and Say
38: Combination Sum
39: Combination Sum II
40: First Missing Positive