Square (DFS) 剪枝

#include<bits/stdc++.h>
using namespace std;

const int Max=20;
int stick[Max];
bool visit[Max];
int m;
int side;

bool DFS(int sum,int number,int p){
    if(number==3){
        cout<<"yes"<<endl;
        return true;
    }
    int error=0;
    for(int i=p;i<m;i++){
        if(visit[i]||sum+stick[i]>side||stick[i]==error){
            continue;
        }
        visit[i]=1;
        if(sum+stick[i]==side){
            if(DFS(0,number+1,0)){
                return 1;
            }
            else{
                error=stick[i];                              //说明这根木棍放在这里不合适。
            }
        }
        else{
            if(DFS(stick[i]+sum,number,p)){
                return 1;
            }
            else{
                error=stick[i];        //说明这根木棍放在这里不合适。
            }
        }
        visit[i]=0;
    }
    return 0;
}

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

int main() {
    int caseN;
    cin>>caseN;
    while(caseN--) {
        memset(visit,0,sizeof(visit));
        int sum=0;
        cin>>m;
        for(int i=0; i<m; i++) {
            cin>>stick[i];
            sum+=stick[i];
        }
        sort(stick,stick+m);
        if(sum%4!=0) {
            cout<<"no"<<endl;
            continue;
        }
        side=sum/4;
        if(stick[0]>side){
            cout<<"no"<<endl;
            continue;
        }
        visit[0]=true;
        if(!DFS(0,0,0)){
            cout<<"no"<<endl;
        }
    }
    return 0;
}