Longest Substring Without Repeating Characters

Example 1:

Input: s = “abcabcbb”
Output: 3
Explanation: The answer is “abc”, with the length of 3.
Example 2:

Input: s = “bbbbb”
Output: 1
Explanation: The answer is “b”, with the length of 1.
Example 3:

Input: s = “pwwkew”
Output: 3
Explanation: The answer is “wke”, with the length of 3.
Notice that the answer must be a substring, “pwke” is a subsequence and not a substring.

class Solution {
public:
    int lengthOfLongestSubstring(string s) {
        string subs=s;
        int len=0;
        int k=0;//起始位置(相对于s)
        int max=0;
        int sum=0;//减去长度总和
        int flag=0;//是否第一次重复；
        for(int i=0;i<s.size();i++)
        {
            int pos=subs.find(s[i]);
            len++;
            if((pos+sum)!=i)
            {
                len=i-k; 
                if(len>max)
                    max=len;
                subs=subs.substr(pos+1,(subs.size()-pos));
                sum+=pos+1;
                // printf("%d#%d#%d#%d",i,pos,k,len);
                k+=sum;
                // cout<<"#"<<subs;
                if(flag==1)
                    len=i-sum+1;//减去之后的长度
                else
                    len=i-pos;
                flag=1;
                // cout<<"#"<<len<<"#"<<sum<<endl;
            }
            if(len>max)
                max=len;
        }
        return max;
    }
};