hdu6298——Maximum Multiple

Given an integer n, Chiaki would like to find three positive integers x, y and z such that: n=x+y+z, x∣n, y∣n, z∣n and xyz is maximum.
Input
There are multiple test cases. The first line of input contains an integer T (1≤T≤106), indicating the number of test cases. For each test case:
The first line contains an integer n (1≤n≤106).
Output
For each test case, output an integer denoting the maximum xyz. If there no such integers, output −1 instead.
Sample Input
3
1
2
3
Sample Output
-1
-1
1

题解的证明看不懂
打表找了一下规律
1 -1
2 -1
3 1=1*1*1
4 2=1*1*2
5 -1
6 8=2*2*2
7 -1
8 16=2*2*4

所以就分为三种情况 %3==0 %4==0 还是else
代码：

#include <cstdio>
#include <algorithm>
using namespace std;
int main(void){
    int t;
    scanf("%d",&t);
    long long n;
    while(t--){
        scanf("%lld",&n);
        if(n%3==0){
            printf("%lld\n",(n/3)*(n/3)*(n/3));
        }
        else if(n%4==0){
            printf("%lld\n",(n/4)*(n/4)*(n/2));
        }
        else{
            printf("-1\n");
        }
    }
    return 0;
}