From b53c047e273a6c516dd1fb3fc938e2967fb9219b Mon Sep 17 00:00:00 2001
From: Ren Baoshuo <i@baoshuo.ren>
Date: Fri, 15 Oct 2021 21:04:07 +0800
Subject: [PATCH] =?UTF-8?q?247.=20=E4=BA=9A=E7=89=B9=E5=85=B0=E8=92=82?=
 =?UTF-8?q?=E6=96=AF?=
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https://www.acwing.com/problem/content/submission/code_detail/8232853/
---
 AcWing/247/247.cpp | 92 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 AcWing/247/247.cpp

diff --git a/AcWing/247/247.cpp b/AcWing/247/247.cpp
new file mode 100644
index 00000000..c96fb37f
--- /dev/null
+++ b/AcWing/247/247.cpp
@@ -0,0 +1,92 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int k, n;
+vector<double> ys;
+
+struct segment {
+    double x, y1, y2;
+    int k;
+
+    segment()
+        : x(0), y1(0), y2(0), k(0) {}
+    segment(double _x, double _y1, double _y2, int _k)
+        : x(_x), y1(_y1), y2(_y2), k(_k) {}
+
+    bool operator<(const segment& b) const {
+        return x < b.x;
+    }
+} seg[10005 << 1];
+
+struct node {
+    int l, r, cnt;
+    double len;
+
+    node()
+        : l(0), r(0), cnt(0), len(0) {}
+    node(int _l, int _r)
+        : l(_l), r(_r), cnt(0), len(0) {}
+} tr[10005 << 3];
+
+int find(double y) {
+    return lower_bound(ys.begin(), ys.end(), y) - ys.begin();
+}
+
+void pushup(int u) {
+    if (tr[u].cnt) {
+        tr[u].len = ys[tr[u].r + 1] - ys[tr[u].l];
+    } else if (tr[u].l != tr[u].r) {
+        tr[u].len = tr[u << 1].len + tr[u << 1 | 1].len;
+    } else {
+        tr[u].len = 0;
+    }
+}
+
+void build(int u, int l, int r) {
+    tr[u] = node(l, r);
+    if (l == r) return;
+    int mid = l + r >> 1;
+    build(u << 1, l, mid);
+    build(u << 1 | 1, mid + 1, r);
+}
+
+void modify(int u, int l, int r, int x) {
+    if (l <= tr[u].l && tr[u].r <= r) {
+        tr[u].cnt += x;
+    } else {
+        int mid = tr[u].l + tr[u].r >> 1;
+        if (l <= mid) modify(u << 1, l, r, x);
+        if (r > mid) modify(u << 1 | 1, l, r, x);
+    }
+    pushup(u);
+}
+
+int main() {
+    while (cin >> n, n) {
+        ys.clear();
+        double ans = 0;
+        cout << "Test case #" << ++k << endl;
+        for (int i = 0, j = 0; i < n; i++) {
+            double x1, y1, x2, y2;
+            cin >> x1 >> y1 >> x2 >> y2;
+            seg[j++] = segment(x1, y1, y2, 1);
+            seg[j++] = segment(x2, y1, y2, -1);
+            ys.push_back(y1);
+            ys.push_back(y2);
+        }
+        sort(ys.begin(), ys.end());
+        ys.erase(unique(ys.begin(), ys.end()), ys.end());
+        build(1, 0, ys.size() - 2);
+        sort(seg, seg + n * 2);
+        for (int i = 0; i < n * 2; i++) {
+            if (i > 0) {
+                ans += tr[1].len * (seg[i].x - seg[i - 1].x);
+            }
+            modify(1, find(seg[i].y1), find(seg[i].y2) - 1, seg[i].k);
+        }
+        cout << "Total explored area: " << fixed << setprecision(2) << ans << endl;
+        cout << endl;
+    }
+    return 0;
+}