Codeforces Round #199 (Div. 2) A Xenia and Divisors

注意题目的数字最大是7 而能整除的只有 1,2,3,4,6,故构成的组合只能是1,2,4 或1,2,6或1,3,6，故分别统计1,2,3,4,6的个数，然后再分配

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

using namespace std;

int main(){
    int n;
    cin >> n ;
    vector<int> a1,a2,a3,a4,a6;
    int tmp;
    for(int i = 0 ; i < n; i ++ ){
        cin >>tmp;
        if(tmp != 1 && tmp !=2 && tmp != 3 && tmp != 4 && tmp!=6) { cout<<-1<<endl; return 0;}
        switch(tmp){
            case 1:
                a1.push_back(tmp);
                break;
            case 2:
                a2.push_back(tmp);
                break;
            case 3:
                a3.push_back(tmp);
                break;
            case 4:
                a4.push_back(tmp);
                break;
            case 6:
                a6.push_back(tmp);
                break;
        }
    }
    int len1 = a1.size(),len2 = a2.size(),len3 = a3.size(),len4 = a4.size(),len6 = a6.size();
    if( (len1=len1-len4)>=0 && (len2=len2 - len4 )>= 0 &&
        (len1= len1-len3)>=0 && (len6 = len6 - len3) >=0 &&
        (len1== len2 && len2 == len6)){
            for(int i = 0; i < a4.size(); ++ i)
                cout<<1<<" "<<2<<" "<<4<<endl;
            for(int i = 0; i < a3.size(); ++ i)
                cout<<1<<" "<<3<<" "<<6<<endl;
            for(int i = 0; i < a6.size()-a3.size(); ++ i)
                cout<<1<<" "<<2<<" "<<6<<endl;
        }
    else{
        cout<<-1<<endl;
    }

    return 0;
}