949. 给定数字能组成的最大时间

class Solution {
public:
    string int_to_string(int a){
        string s = "";
        if(a == -1) return s;
        for(int i = 1000; i >= 1; i/=10){
            int b = a / i;
            if(i == 10)
                s += ":";
            s += ('0' + b);
            a = a % i;
        }
        return s;
    }
    
    string largestTimeFromDigits(vector<int>& A) {
        int i = 0;
        int res = -1;
            
        for(int i = 0; i < A.size(); i++){
            for(int j = 0; j < A.size(); j++){
                if(i == j) continue;
               for(int k = 0; k < A.size(); k++){
                   if(k == i || k == j) continue;
                   for(int m = 0; m <A.size(); m++){
                       if(m == i || m == j || m == k)continue;
                       int hour = A[i] * 10 + A[j]; 
                       int minute = A[k] * 10 + A[m];
                       int temp = hour * 100 + minute;
                       if(hour < 24 && minute < 60 && temp > res) 
                           res = temp;
                   }
               }
            }
        }
        return int_to_string(res);
    }
};