#include <cstdio> #include <iostream> #include <algorithm> #include <cstring> using namespace std; const int MAXN = 25; int sticks[MAXN]; bool visit[MAXN]; int m; int side; bool Compare(int x,int y){return x>y; } bool DFS(int sum,int number,int position){ //sum 当前拼凑的木棍长度，number 已拼凑出的边长，position 当前木棍的编号if(number == 3){return true;}int sample = 0 ; //记录失败的木棍长度，下次再遇到直接跳过。for(int i = position; i < m ; i++){ //从上一位置接着寻找if(visit[i] || sum +sticks[i] > side || sticks[i] == sample){//在凑成一条边的路径中continue;}visit[i] = true;if(sum + sticks[i] == side){ //一条边已经凑齐if(DFS(0,number+1,0)){ //当一条边已经凑齐了之后，重新开始另一条边要从头开始查找可以使用的木棍return true;}else {sample = sticks[i];}} else {if(DFS(sum + sticks[i],number,i+1)){ //一条边没有凑齐，继续凑下一个木棍return true;}else {sample = sticks[i];}}visit[i] = false;}return false; } int main() {int n ;cin>>n;while(n--){cin>>m;int length =0;for(int i = 0 ; i < m; i++){cin>>sticks[i];length += sticks[i];}if(length % 4 != 0){cout<<"no"<<endl;continue;}side = length/4;sort(sticks,sticks + m,Compare);if(sticks[0] > side){cout<<"no"<<endl;continue;}memset(visit,false,sizeof(visit));if(DFS(0,0,0)){cout<<"yes"<<endl;}else {cout<<"no"<<endl;}}return 0; }
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