Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. For "bbbbb" the longest substring is "b", with the length of 1.
题解：贪心算法。
利用一个hashmap存放当前最长的无重substring所包含的元素，变量leftbound存放当前的最左边界。则当前遍历的字符s[i]有两种情况：
代码如下：
1 public class Solution { 2 public int lengthOfLongestSubstring(String s) { 3 if(s == null || s.length() == 0) 4 return 0; 5 6 HashMap<Character, Integer> map = new HashMap<Character, Integer>(); 7 int leftebound = 0; 8 int answer = 0; 9 10 for(int i = 0;i < s.length();i++){ 11 char current = s.charAt(i); 12 if(map.containsKey(s.charAt(i))){ 13 while(s.charAt(leftebound) != current && leftebound < i){ 14 map.remove(s.charAt(leftebound)); 15 leftebound++; 16 } 17 leftebound++; 18 } 19 else { 20 map.put(current, 0); 21 answer = Math.max(i-leftebound+1, answer); 22 } 23 } 24 25 return answer; 26 } 27 }
【leetcode刷题笔记】Longest Substring Without Repeating Characters,布布扣,bubuko.com
【leetcode刷题笔记】Longest Substring Without Repeating Characters
原文：http://www.cnblogs.com/sunshineatnoon/p/3863134.html