洛谷P1378 油滴扩展

Posted 2020-09-17 lonlyn

题目：https://www.luogu.org/problem/show?pid=1378

因为n<=6，所以只需要暴力枚举每一种排列即可。

 

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<cmath>
 5 #define pi 3.1415926535897932384
 6 using namespace std;
 7 
 8 int n;
 9 double x,y,x2,y2;  //x,y left up x1,y1 right down
10 double xx[10],yy[10];
11 double ans=0;
12 
13 int vis[10];
14 double nx[10],ny[10],nr[10];
15 
16 void dfs(int step,double s){
17     if (step==n+1){
18         ans=max(ans,s);
19         return;
20     }
21     for (int i=1;i<=n;++i)
22     if (!vis[i]){
23         vis[i]=1;
24         nx[step]=xx[i],ny[step]=yy[i];
25         nr[step]=min(min(x2-nx[step],nx[step]-x),min(y2-ny[step],ny[step]-y));
26         //cout<<nr[i]<<endl;
27         for (int j=1;j<=step-1;++j){
28             nr[step]=min(nr[step],sqrt((nx[step]-nx[j])*(nx[step]-nx[j])+(ny[step]-ny[j])*(ny[step]-ny[j]))-nr[j]);
29             if (nr[step]<=0){
30                 nr[step]=0;
31                 break;
32             }
33         }
34         dfs(step+1,s+pi*nr[step]*nr[step]);
35         vis[i]=0;
36     }
37 }
38 
39 int main(){
40     scanf("%d",&n);
41     scanf("%lf%lf%lf%lf",&x,&y,&x2,&y2);
42     if (x>x2) swap(x,x2);
43     if (y>y2) swap(y,y2);
44     for (int i=1;i<=n;++i){
45         scanf("%lf%lf",&xx[i],&yy[i]);
46     }
47     dfs(1,0);
48     printf("%.0lf",(x2-x)*(y2-y)-ans);
49     return 0;
50 }

戳我>_<