3 4 1 1 1 1 5 10 20 30 40 50 8 1 7 2 6 4 4 3 5
yes no yes
#include<iostream> #include<cstring> using namespace std; int v[23],n,flag; int a[23],sum; void dfs(int p,int ans,int t) { if(ans==sum/4) { p++; // cout<<p<<"-------\n"; if(p==4) { flag=1; return ; } else ans=0; t=0; } if(flag) return ; for(int i=t;i<n;i++) if(!v[i] && a[i]+ans<=sum/4) { v[i]=1; // cout<<ans+a[i]<<" "; dfs(p,ans+a[i],i); v[i]=0; } } int main() { int T; cin>>T; while(T--) { cin>>n; int max; max=sum=0; for(int i=0;i<n;i++) { cin>>a[i]; sum += a[i]; if(max<a[i]) max=a[i]; } if(sum%4!=0 || max>sum/4) cout<<"no\n"; else { memset(v,0,sizeof(v)); flag=0; dfs(0,0,0); if(flag) cout<<"yes\n"; else cout<<"no\n"; } } return 0; }
杭电 1518 Square (深搜)(回溯),布布扣,bubuko.com
原文地址:http://blog.csdn.net/u012766950/article/details/38147161