LeetCode 3. Longest Substring Without Repeating Characters

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.

就是算最长的元素不重复子串的长度。

class Solution {
public:
int lengthOfLongestSubstring(string s) {
int len = s.length();
int ans = 0;
bool flag;
bool vis[500];
for(int i=0; i<len; i++){
flag = true;
memset(vis,0,sizeof(vis));
for(int j=i+1; j<len; j++){
if(s[j]==s[i]||vis[s[j]]){
ans=ans>(j-i)?ans:(j-i);
flag = false;
break;
}
vis[s[j]]=true;
}
if(flag){
ans=ans>(len-i)?ans:(len-i);
}
}
return ans;
}
};