From b921ccfe85a225d7c7fda1ea67df705d7cae8784 Mon Sep 17 00:00:00 2001
From: Baoshuo <i@baoshuo.ren>
Date: Tue, 4 Oct 2022 21:40:39 +0800
Subject: [PATCH] =?UTF-8?q?P3620=20[APIO/CTSC2007]=20=E6=95=B0=E6=8D=AE?=
 =?UTF-8?q?=E5=A4=87=E4=BB=BD?=
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https://www.luogu.com.cn/record/88613869
---
 Luogu/P3620/P3620.cpp | 72 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 Luogu/P3620/P3620.cpp

diff --git a/Luogu/P3620/P3620.cpp b/Luogu/P3620/P3620.cpp
new file mode 100644
index 00000000..d91d2cdb
--- /dev/null
+++ b/Luogu/P3620/P3620.cpp
@@ -0,0 +1,72 @@
+#include <iostream>
+#include <limits>
+#include <queue>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 100005;
+
+int n, k, a[N], pre[N], suf[N];
+long long c[N], ans;
+std::priority_queue<
+    std::pair<int, long long>,
+    std::vector<std::pair<int, long long>>,
+    auto(*)(std::pair<int, long long>, std::pair<int, long long>)->bool>
+q([](std::pair<int, long long> a, std::pair<int, long long> b) -> bool {
+    return a.second > b.second;
+});
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> k;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+
+    for (int i = 1; i < n; i++) {
+        c[i] = static_cast<long long>(a[i + 1]) - a[i];
+        pre[i] = i - 1;
+        suf[i] = i + 1;
+    }
+    suf[n - 1] = 0;
+
+    for (int i = 1; i < n; i++) {
+        q.emplace(i, c[i]);
+    }
+
+    while (k--) {
+        auto o = q.top();
+        q.pop();
+
+        if (o.second != c[o.first]) {
+            k++;
+
+            continue;
+        }
+
+        ans += o.second;
+
+        int l = pre[o.first],
+            r = suf[o.first];
+
+        suf[o.first] = suf[r];
+        pre[suf[o.first]] = o.first;
+        pre[o.first] = pre[l];
+        suf[pre[o.first]] = o.first;
+
+        c[o.first] = (l && r) ? std::min(static_cast<long long>(std::numeric_limits<int>::max()), c[l] + c[r] - c[o.first]) : std::numeric_limits<int>::max();
+        c[l] = c[r] = std::numeric_limits<int>::max();
+
+        q.emplace(o.first, c[o.first]);
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}