题解 | 字符个数统计

#include <iostream>
#include <string>
#include <algorithm>

int main(){
    std::string s, subs;
    int count = 0;
    std::cin >> s;
    for(char c: s){
        if(std::find(subs.begin(), subs.end(), c) == subs.end()){
            subs.push_back(c);
            count ++;
        }
    }
    std::cout << count;
    return 0;
}