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.

思路：标记字符串visit[(int)s[i]]=i;

#include <iostream>
#include <cstdio>
#include <cstring>
#include<vector>
using namespace std;
int maxindex=0;
class Solution
{
public:
int lengthOfLongestSubstring(string s)
{
int len=s.length();
if(len==0)
return 0;
int visit[256];
memset(visit,-1,sizeof(visit));
int maxlen=0;
int curlen=0;
int last_start=0;
for(int i=0; i<len; i++)
{
if(visit[(int)s[i]]==-1)
{
curlen++;
visit[(int)s[i]]=i;
}
else
{
if(last_start<=visit[(int)s[i]]) //当前最长串中包括该重复字符s[]
{
last_start=visit[(int)s[i]]+1;
curlen=i-visit[(int)s[i]];
visit[(int)s[i]]=i;
}
else //出现过arr[i]但不在当前最长串中
{
curlen++;
visit[(int)s[i]]=i;
}
}
if(curlen>maxlen)
{
maxlen=curlen;
//maxindex=i+1-maxlen;
}

}
return maxlen;
}

};

int main()
{
string s="abcaacdeabacdefg{}dewifh01kw{}";
Solution sol;
int i = sol.lengthOfLongestSubstring(s);
while(i--)
{
printf("%c",s[maxindex++]);
}
printf("\n");
}