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OI-codes/XJOI/contest/21med/C/C.cpp

34 lines
813 B
C++

#include <bits/stdc++.h>
using namespace std;
int n;
long long ans, cnt, x;
pair<long long, long long> q[300005];
bool cmp(pair<long long, long long> a, pair<long long, long long> b) {
return (a.first - b.first) * (a.second + b.second) > (a.first + b.first) * (a.second - b.second);
}
int main() {
cin >> n;
for (int i = 0; i < n; i++) {
cin >> q[i].first >> q[i].second;
}
sort(q, q + n, cmp);
for (int i = 0; i < n; i++) {
cnt += abs(2 * q[i].second * x + q[i].second * q[i].first);
x += q[i].first;
}
ans = max(ans, cnt);
x = 0;
cnt = 0;
for (int i = n - 1; i >= 0; i--) {
cnt += abs(2 * q[i].second * x + q[i].second * q[i].first);
x += q[i].first;
}
ans = max(ans, cnt);
cout << ans << endl;
return 0;
}