蓝桥杯省赛 训练士兵 19703 刷子法+贪心

传送门 0训练士兵 - 蓝桥云课

const int N = 1e5 + 10;


LL n,s;
struct Node
{
	LL p,c;
	bool operator< (const Node &t) const
	{
		return c < t.c;
	}
}a[N];

void solve()
{
	cin >> n >> s;
	LL sum = 0;//还需训练的士兵的总代价
	for (int i = 1;i <= n;i ++)
	{
		LL p,c;cin >> p >> c;
		a[i] = {p,c};
		sum += p;
	}
	
	sort(a + 1,a + 1 + n);//按照训练次数从小到大排序
	
	LL ans = 0,t = 0;//t:当前全部士兵一起已经训练的次数
	for (int i = 1;i <= n;i ++)
	{
		if (s <= sum)
		{
			ans += s * (a[i].c - t);
			t += a[i].c - t;
			sum -= a[i].p;//这个士兵已经顶级
		}
		else
		{
			ans += (a[i].c - t) * a[i].p;
		}
	}
	
	cout << ans << endl;
}