nyoj 43 24 Point game

来源：互联网发布：战争是必然的知乎编辑：程序博客网时间：2024/05/16 01:44

http://acm.nyist.net/JudgeOnline/problem.php?pid=43

分析：因为精度改了一天，我说怎么看逻辑都没有问题……

加、减、乘、除、被加、被减，然后遍历

#include <iostream>#include <cstdio>#include <cstring>#include <cmath>using namespace std;const int NM=15;const double eps=1e-6;bool vis[NM],flag;double a[NM];int n,m,k;void DFS(double ans,int num){if(flag) return;if(num==n){if(fabs(ans-m)<eps)  //！！flag=true;return;}for(int i=1;i<=n;i++){if(!vis[i]){vis[i]=1;if(num==0) DFS(a[i],num+1);else{for(int j=0;j<6;j++){switch(j){case 0:DFS(ans+a[i],num+1);break;case 1:DFS(ans*a[i],num+1);break;case 2:DFS(ans-a[i],num+1);break;case 3:DFS(a[i]-ans,num+1);break;case 4:if(a[i]!=0) DFS(ans/a[i],num+1);break;case 5:if(ans!=0) DFS(a[i]/ans,num+1);break;}}}vis[i]=0;  //}}}int main(){int T,i;scanf("%d",&T);while(T--){cin>>n>>m;for(i=1;i<=n;i++) cin>>a[i];flag=false;DFS(0,0);if(flag) cout<<"Yes"<<endl;else cout<<"No"<<endl;}return 0;}

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