T263132 购物

https://www.luogu.com.cn/record/85551702

Luogu/T263132/T263132.cpp

@@ -0,0 +1,74 @@
+#include <iostream>
+#include <algorithm>
+#include <queue>
+#include <utility>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 50005;
+
+int n, k;
+long long m, sum;
+std::pair<long long, long long> a[N];
+std::priority_queue<long long, std::vector<long long>, std::greater<long long>> q;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> k >> m;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i].first >> a[i].second;
+    }
+
+    std::sort(a + 1, a + n + 1, [](auto a, auto b) {
+        return a.second < b.second;
+    });
+
+    for (int i = 1; i <= k; i++) {
+        sum += a[i].second;
+
+        q.push(a[i].first - a[i].second);
+
+        if (sum > m) {
+            cout << i - 1 << endl;
+
+            exit(0);
+        } else if (i == n) {
+            cout << n << endl;
+
+            exit(0);
+        }
+    }
+
+    std::sort(a + k + 1, a + n + 1, [](auto a, auto b) {
+        return a.first < b.first;
+    });
+
+    for (int i = k + 1; i <= n; i++) {
+        auto x = q.top();
+
+        sum += a[i].first;
+
+        if (a[i].second + x < a[i].first) {
+            q.pop();
+
+            auto y = a[i].first - a[i].second;
+            q.push(y);
+            sum += x - y;
+        }
+
+        if (sum > m) {
+            cout << i - 1 << endl;
+
+            exit(0);
+        }
+    }
+
+    cout << n << endl;
+
+    return 0;
+}