leetcode+求最大无重复字母字串+n^2,循环记得标记，循环有点像最长上升子序列

#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<string>
#include<cstring>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<queue>
#include<vector>
#include<set>
#define LL long long
#define inf 0x3f3f3f3f
#define mod 1e9+7
using namespace std;
class Solution {
public:
int lengthOfLongestSubstring(string s) {
int num=0,i=0,j=0,index=0,len=0;
len = s.length();
if(len==0) return 0;
if(len==1) return 1;
for(i=1;i<len;i++){
for(j=i-1;j>=index;j--){
if(s[j]==s[i]){
index=j+1;
break;
}
else{
num=max(num,i-j+1);
}
}
}
return max(num,1); ///避免那种bbbb的情况
}
};
int main()
{
char s[100];
scanf("%s",s);
Solution temple;
cout<<temple.lengthOfLongestSubstring(s)<<endl;
return 0;
}