算法提高 最大乘积

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
int a[20];
int main()
{
	int n,i,ans,m,k;
	scanf("%d",&k);
	while(k--){
		scanf("%d%d",&n,&m);
		for(i=0;i<n;++i){
			scanf("%d",&a[i]);
		}
		sort(a,a+n);ans=1;
		int value=1,result=1,e=0,g=n-1,t=0;
		if(m%2==0){
			while(t!=m){
				value=a[e]*a[e+1];result=a[g]*a[g-1];
				if(value>result){
					ans*=value;e+=2;
				}
				else {
					ans*=result;g-=2;
				}
			t+=2;
			}
		printf("%d\n",ans);
		}
		else {
			m=m-1;g=g-1;
			while(t!=m){
				value=a[e]*a[e+1];result=a[g]*a[g-1];
				if(value>result){
					ans*=value;e+=2;
				}
				else {
					ans*=result;g-=2;
				}
			t+=2;
			}
		printf("%d\n",ans*a[n-1]);
		}
	}
	return 0;
}