[剑指 offer] JT34---The first character that appears only once (not before, and also after)

The topic is as follows

Idea and code

Idea 1: This is related to the number of times. Everyone should think of map, save, and then search one by one.
Idea 2: But for strings, he has a find function that can be used, that is, we can use the entire character If you find it only once in the string, it is the answer. The display is very simple, just go to the code

class Solution {
    
    
public:
    int FirstNotRepeatingChar(string str) {
    
    
        int len=str.length();
        if(!len) return -1;
        int i;
        for(i=0;i<str.length();i++){
    
    
            if(str.find(str[i],0)==i&&str.find(str[i],i+1)==-1)
                break;
        }
        if(i==len) return -1;
        else return i;
    }
};