P5094 [USACO04OPEN] MooFest G 加强版

https://www.luogu.com.cn/record/77636702

Luogu/P5094/P5094.cpp

@@ -0,0 +1,54 @@
+#include <iostream>
+#include <algorithm>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 5e4 + 5;
+
+int n;
+long long c1[N], c2[N], s, ans;
+std::pair<int, int> p[N];
+
+inline int lowbit(int x) {
+    return x & -x;
+}
+
+void add(long long* c, int x, int y) {
+    for (; x <= 5e4; x += lowbit(x)) c[x] += y;
+}
+
+long long sum(long long* c, int x) {
+    long long res = 0;
+    for (; x; x -= lowbit(x)) res += c[x];
+    return res;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> p[i].first >> p[i].second;
+    }
+
+    std::sort(p + 1, p + 1 + n);
+
+    for (int i = 1; i <= n; i++) {
+        int a = sum(c1, p[i].second),
+            b = sum(c2, p[i].second);
+
+        ans += ((a * p[i].second - b) + ((s - b) - (i - a - 1) * p[i].second)) * p[i].first;
+
+        add(c1, p[i].second, 1);
+        add(c2, p[i].second, p[i].second);
+        s += p[i].second;
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}