From 15dcd64d26173d40ae64d9f21b9b7937e54a2c94 Mon Sep 17 00:00:00 2001
From: Baoshuo <i@baoshuo.ren>
Date: Thu, 16 Jun 2022 11:26:29 +0800
Subject: [PATCH] =?UTF-8?q?P2831=20[NOIP2016=20=E6=8F=90=E9=AB=98=E7=BB=84?=
 =?UTF-8?q?]=20=E6=84=A4=E6=80=92=E7=9A=84=E5=B0=8F=E9=B8=9F?=
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https://www.luogu.com.cn/record/77450202
---
 Luogu/P2831/P2831.cpp | 69 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 Luogu/P2831/P2831.cpp

diff --git a/Luogu/P2831/P2831.cpp b/Luogu/P2831/P2831.cpp
new file mode 100644
index 00000000..a01277ff
--- /dev/null
+++ b/Luogu/P2831/P2831.cpp
@@ -0,0 +1,69 @@
+#include <iostream>
+#include <cstring>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 20;
+const double eps = 1e-6;
+
+int t, n, m, cnt, f[1 << N], s[N << 4];
+std::pair<double, double> points[N];
+
+inline std::pair<double, double> e(const std::pair<double, double> &_a, const std::pair<double, double> &_b) {
+    return std::make_pair(
+        (_a.second - _b.second * _a.first / _b.first) / (_a.first * (_a.first - _b.first)),
+        (_a.second - _b.second * _a.first * _a.first / (_b.first * _b.first)) / (_a.first - _a.first * _a.first / _b.first));
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> t;
+
+    while (t--) {
+        cnt = 0;
+        memset(f, 0x3f, sizeof(f));
+        memset(s, 0x00, sizeof(s));
+
+        cin >> n >> m;
+
+        for (int i = 0; i < n; i++) {
+            cin >> points[i].first >> points[i].second;
+        }
+
+        for (int i = 0; i < n; i++) {
+            for (int j = i + 1; j < n; j++) {
+                if (std::abs(points[i].first - points[j].first) < eps) continue;
+
+                auto r = e(points[i], points[j]);
+                if (r.first > -eps) continue;
+
+                cnt++;
+                for (int k = 0; k < n; k++) {
+                    if (std::abs(r.first * points[k].first * points[k].first + r.second * points[k].first - points[k].second) < eps) {
+                        s[cnt] |= 1 << k;
+                    }
+                }
+            }
+        }
+
+        f[0] = 0;
+        for (int i = 0; i < 1 << n; i++) {
+            // 两只及以上
+            for (int j = 1; j <= cnt; j++) {
+                f[i | s[j]] = std::min(f[i | s[j]], f[i] + 1);
+            }
+            // 一只
+            for (int j = 0; j < n; j++) {
+                f[i | 1 << j] = std::min(f[i | 1 << j], f[i] + 1);
+            }
+        }
+
+        cout << f[(1 << n) - 1] << endl;
+    }
+
+    return 0;
+}