Given a string, find the length of the longest substring without repeating characters.
Examples:
Given "abcabcbb", the answer is "abc", which the length is 3.
Given "bbbbb", the answer is "b", with the length of 1.
Given "pwwkew", the answer is "wke", with the length of 3. Note that the answer must be a substring, "pwke" is a subsequence and not a substring.
public class Solution { public int lengthOfLongestSubstring(String s) { int dp[] = new int[128]; //indicated the latest appearance of 128 ASCII letter int start = 0; //start position of current traverse int maxLength = 0; int curLength = 0; for(int i = 0; i < dp.length; i++){ //不能使用int i:a, 因为遍历的i会被改变值 dp[i] = -1; //initialized as -1 } for(int i = 0; i < s.length(); i++){ if(dp[s.charAt(i)] < start) { //haven‘t repeated in the current traverse dp[s.charAt(i)]=i; } else{ //repeat occurs if(i-start > maxLength){ maxLength = i-start; } //reset start = dp[s.charAt(i)]+1; dp[s.charAt(i)] = i; } } if(s.length()-start > maxLength){ //final traverse substring maxLength = s.length()-start; } return maxLength; } }
3. Longest Substring Without Repeating Characters
原文：http://www.cnblogs.com/qionglouyuyu/p/5452968.html