## 问题链接

Longest Substring Without Repeating Characters

## 问题描述

``````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.

``````

## 解决办法

``````public class Solution {
public int lengthOfLongestSubstring(String s) {
int lp = 0;
String sp = "";
while (s.length() > 0) {
String a = Character.toString(s.charAt(0));
s = s.substring(1);
int j = sp.indexOf(a);
if (j > -1) {
lp = Math.max(lp, sp.length());
sp = sp.substring(j + 1) + a;
} else {
sp += a;
}
}
return Math.max(lp, sp.length());
}
}``````

``````public class Solution {
public int lengthOfLongestSubstring(String s) {
if (s.length()==0) return 0;
HashMap<Character, Integer> map = new HashMap<Character, Integer>();
int max=0;
for (int i=0, j=0; i<s.length(); ++i){
if (map.containsKey(s.charAt(i))){
j = Math.max(j,map.get(s.charAt(i))+1);
}
map.put(s.charAt(i),i);
max = Math.max(max,i-j+1);
}
return max;
}
}
``````