题解：P14635 [NOIP2025] 糖果店 / candy

#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 1e5 + 5;
int n, x[N], y[N];
ll ans, ansy, minn = 1e10, sum, m;
int main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n >> m;
    for(int i = 1;i <= n;i++){
    	cin >> x[i] >> y[i];
        //找最小的每一组糖果的价格
    	if(x[i] + y[i] < minn){
    		minn = x[i] + y[i];
		}
	}
    //先算当前的 ans，但不是最优的
	ans = m / minn * 2, m %= minn, ansy = ans;
    //选x[i]的时候显然要从小的买
	sort(x + 1, x + n + 1);
	for(int i = 1;i <= n;i++){
		sum += x[i];
		ll th;
		//算买价格 sum 的糖果要退回多少个 minn
		if(m >= sum) th = 0;
		else if((sum - m) % minn == 0) th = (sum - m) / minn;
		else th = (sum - m) / minn + 1;
		//更新 ans 看会不会更优 
		if(th <= ans * 2 && ans - th * 2 + i > ansy){
			ansy = ans - th * 2 + i;
		}
	}
	cout << ansy;
	return 0;
}