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55 lines
1015 B
C++
55 lines
1015 B
C++
#include <iostream>
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#include <algorithm>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 5e4 + 5;
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int n;
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long long c1[N], c2[N], s, ans;
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std::pair<int, int> p[N];
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inline int lowbit(int x) {
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return x & -x;
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}
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void add(long long* c, int x, int y) {
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for (; x <= 5e4; x += lowbit(x)) c[x] += y;
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}
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long long sum(long long* c, int x) {
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long long res = 0;
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for (; x; x -= lowbit(x)) res += c[x];
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return res;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n;
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for (int i = 1; i <= n; i++) {
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cin >> p[i].first >> p[i].second;
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}
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std::sort(p + 1, p + 1 + n);
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for (int i = 1; i <= n; i++) {
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int a = sum(c1, p[i].second),
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b = sum(c2, p[i].second);
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ans += ((a * p[i].second - b) + ((s - b) - (i - a - 1) * p[i].second)) * p[i].first;
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add(c1, p[i].second, 1);
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add(c2, p[i].second, p[i].second);
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s += p[i].second;
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}
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cout << ans << endl;
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return 0;
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}
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