JZYZOJ1384 种花小游戏 状压dp

http://172.20.6.3/Problem_Show.asp?id=1384

 最开始以为是dfs然后超时了，然后调了半天调成dp，还不如再写一遍。。。

代码

#include<iostream>  
#include<cstdio>  
#include<cstring>  
#include<algorithm>  
#include<cmath>  
using namespace std;
const int maxn=1<<25;
int n,x,y;
int a[20][2]={};
double f[(1<<16)+10][20]={};
int vis[20]={};
double ans=(1<<30);
int main(){
    scanf("%d",&n);int x,y;
    for(int i=0;i<n;i++){
        scanf("%d%d",&a[i][0],&a[i][1]);
    }scanf("%d%d",&x,&y);
    int ma=1<<n;
    for(int i=1;i<ma;i++){
        for(int j=0;j<n;j++){
            f[i][j]=1.0*maxn;
        }
    }
    int x1,x2;double y1,y2,wtf;
    for(int i=0;i<n;i++){
        x1=1<<i;
        y1=(double)abs(a[i][0]-x);y2=(double)abs(a[i][1]-y);
        wtf=sqrt((double)y1*y1+y2*y2);
        f[x1][i]=wtf;
    }int wt=1;
    for(int i=1;i<ma;i++){
        if(i==wt){wt*=2;continue;}
        for(int j=0;j<n;j++){
            x1=1<<j;if((x1|i)!=i)continue;
            for(int w=0;w<n;w++){
                x2=1<<w;
                if((x2|i)!=i||w==j)continue;
                y1=(double)abs(a[j][0]-a[w][0]);y2=(double)abs(a[j][1]-a[w][1]);
                wtf=sqrt((double)y1*y1+y2*y2);
                if(f[i-x1][w]+wtf-f[i][j]<0){
                    f[i][j]=f[i-x1][w]+wtf;
                }
            }
        }
    }double ans=maxn;
    for(int i=0;i<n;i++){
        if(f[ma-1][i]<ans)ans=f[ma-1][i];
    }
    printf("%.2f",ans);
    return 0;
}