[DP] 백준 2180 소방서의 고민 C++

 

https://www.acmicpc.net/problem/2180

#include<iostream>
#include<vector>
#include<algorithm>
#define MAX 100001
using namespace std;

int n ,a, b;
int ans;
vector<pair<int, int>> v;

bool cmp(pair<int, int> p, pair<int, int> q) {
    int a = p.first, b = p.second, c = q.first, d = q.second;
    if (a == 0) return false;
    else if (c == 0) return true;
    else if ((b == 0) && (d == 0))  return a < c;
    return b * c < a * d;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);

    cin >> n;

    for (int i = 0; i < n; i++) {
        cin >> a >> b;
        v.push_back({ a,b });
    }
    sort(v.begin(), v.end(), cmp);

    a = 0;
    for (int i = 0; i < n; i++) {
        a = v[i].first * ans + v[i].second;
        ans += a;
        ans %= 40000;
    }

    cout << ans;

}