hdu 1518 Square

Square

Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 8260 Accepted Submission(s): 2687

Problem Description Given a set of sticks of various lengths, is it possible to join them end-to-end to form a square?

Input The first line of input contains N, the number of test cases. Each test case begins with an integer 4 <= M <= 20, the number of sticks. M integers follow; each gives the length of a stick - an integer between 1 and 10,000.

Output For each case, output a line containing "yes" if is is possible to form a square; otherwise output "no".

Sample Input

3
4 1 1 1 1
5 10 20 30 40 50
8 1 7 2 6 4 4 3 5

Sample Output

yes
no
yes

#include
#include
#include
using namespace std;
#define M 25
int a[M],vis[M];
int n,m,sum;

bool cmp(int x,int y)
{
	return (x>y);
}

int dfs(int ans,int cur,int num)  //ans表示當前位置 cur表示當前權值 num表示邊數
{  
	int i;
	if(num==4) return 1;
	for(i=ans;i>t;
	while(t--)
	{
		cin>>n;
		sum=0;
		for(i=0;i>a[i];
			sum+=a[i];
		}
		if(sum%4!=0)
			printf("no\n");
		else
		{
			m=sum/4;    // 邊長
			sort(a,a+n,cmp);
			if(m