The longest substring of sword finger offer without repeated characters

The longest substring without repeating characters

describe ：
Please find the longest substring in the string that does not contain duplicate characters , Calculate the length of the longest substring .

Answer key ：
Maintain a map Used to store the traversed characters and subscripts
maxlen Used to store the maximum length value
curlen Used to store the length of the non repeating string being traversed
There are three situations ：

• The current character has not appeared , That is to say map There is no information about this character in , here curlen++
• The current character minus the subscript of the last occurrence of this character is greater than curlen, It indicates that the last time this character appeared, it was in the non repeating string of the previous calculation , That is, this character is not repeated ,curlen++
• The current character has appeared in the calculation of this non repeating string , The description has been repeated ,curlen=i-index

class Solution {
public:
    /**
     *  The class name in the code 、 Method name 、 The parameter name has been specified , Do not modify , Return the value specified by the method directly 
     *
     * 
     * @param s string character string  
     * @return int integer 
     */
    int lengthOfLongestSubstring(string s) {
        // write code here
        map<char, int> index;
        int maxlen=0,curlen=0;
        for(int i=0;i<s.length();i++){
            if(index.find(s[i])==index.end()){
                curlen++;
            }else if(i-index[s[i]]>curlen){
                curlen++;
            }else{
                curlen=i-index[s[i]];
            }
            if(curlen>maxlen){
                maxlen=curlen;
            }
            // If it doesn't appear, it's to index Add elements to it , Once it appears, it is updated index value 
            index[s[i]]=i;
        }
        return maxlen;
    }
};