最长无重复字符子串

题目出自leetcode第三题

https://leetcode.com/problems/longest-substring-without-repeating-characters/

解题思路：

1、以第0,1,...,n个字符结尾的无重复字符子串中最长的即为最长无重复字符子串

记以第0,1,...,n个字符结尾的无重复字符子串为s(i)，首字符位置为start(i)，长度即为i-start(i)+1;

2、s(i+1)的start(i+1)为第i+1个字符在s(i)中出现的位置，否则为start(i);

代码：

<span style="white-space:pre"></span>public int lengthOfLongestSubstring(String s) {if(s==null||s.equals(""))return 0;int length = 1;for(int start=0,end = 1; end<s.length(); end++){start = find(s,start,end);if(end-start+1>length)length = end-start+1;}return length;    <span style="white-space:pre"></span>}public int find(String s, int start, int end){int i = start;for(;i<end;i++){if(s.charAt(i)==s.charAt(end))break;}if(i==end)return start;else return i+1;}