DFS题目，用到了全排列模型。

全排列模板：

全排列https://blog.csdn.net/qq_55799677/article/details/121147416

测试样例：

2
20 0 10 10
13 3
17 7

样例输出：

50

代码：

#include<iostream>
#include<string>
using namespace std;
#define Pi 3.1415926
const int N = 10 + 5;
int n, vis[N];
double R[N], ans;
int xa, ya, xb, yb;struct node {int x, y;
}p[N];double cal(int i) //计算R[i]
{double r1 = min(abs(p[i].x - xa), abs(p[i].x - xb));double r2 = min(abs(p[i].y - ya), abs(p[i].y - yb));double r = min(r1, r2);for (int j = 1; j <= n; j++){if (i != j && vis[j]) {double d = sqrt(abs(pow(p[i].x - p[j].x, 2)) + abs(pow(p[i].y - p[j].y, 2)));r = min(r, max(0.0, d - R[j]));}}return r;
}// 全排列模型
void dfs(int x, double s)
{if (x > n) {ans = max(ans, s); // 搜索面积最大值return;}for (int i = 1; i <= n; i++){if (!vis[i]) {vis[i] = 1;R[i] = cal(i);dfs(x + 1, s + Pi * R[i] * R[i]);vis[i] = 0;}}
}int main()
{ios::sync_with_stdio(false);cin >> n;cin >> xa >> ya >> xb >> yb;for (int i = 1; i <= n; i++) {cin >> p[i].x >> p[i].y;}dfs(1, 0.0);double s = abs(xa - xb) * abs(ya - yb);cout << int(s - ans + 0.5);return 0;
}