摘要： Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999. 阅读全文

摘要： Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 阅读全文

摘要： Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpo 阅读全文

摘要： Implement regular expression matching with support for '.' and '*'. 思路：在出现*的时候，因为可能出现0，1，2，...次，所以要使用到带回溯的递归 阅读全文

摘要： Determine whether an integer is a palindrome. Do this without extra space. 阅读全文

摘要： Implement atoi to convert a string to an integer. If no valid conversion could be performed, a zero value is returned. If the correct value is out of 阅读全文

摘要： Reverse digits of an integer. Example1: x = 123, return 321Example2: x = -123, return -321 For the purpose of this problem, assume that your function 阅读全文

摘要： The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font 阅读全文

摘要： Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longes 阅读全文

摘要： There are two sorted arrays nums1 and nums2 of size m and n respectively. Find the median of the two sorted arrays. The overall run time complexity sh 阅读全文