题解 | 请客吃饭

#include <bits/stdc++.h>

using namespace std;

#define int long long
int ans = 1e9 + 5;			//最小隔阂
int maxhp = 0;				//最大愉悦

void solve()
{
	int n, k; cin >> n >> k;
	vector<pair<int,int>> a(n + 1,{0,0}), b(n + 1, {0,0});

	for (int i = 1; i <= n; i++)			//输入财富，second是下表
	{
		cin >> a[i].first;
		a[i].second = i;
	}
	for (int i = 1; i <= n; i++)			//输入愉悦值，second是下表
	{
		cin >> b[i].first;
		b[i].second = i;
	}
	sort(a.begin() + 1, a.begin() + 1 + n);	//按照财富排序

	vector<int> pre(n + 1, 0);
	for (int i = 1; i <= n; i++)			//财富排序后的愉悦值前缀和
	{
		int idx = a[i].second;
		pre[i] = b[idx].first + pre[i - 1];
	}
	int l = 1, r = 1;
	while (l <= n && r <= n)
	{
		int idxr = a[r].second, idxl = a[l].second;	//计算原始下表
		int hp = pre[r] - pre[l - 1];				//计算愉悦值
		if (hp < k)
		{
			r++;
		}
		else
		{
			if (hp >= maxhp)
				ans = min(ans, abs(a[r].first - a[l].first));	//更新最小隔阂
			else
				maxhp = hp;
			l++;
		}
	}
	if (ans == 1e9 + 5)
		cout << -1;
	else
		std::cout << ans << endl;
}
signed main()
{
	solve();
	return 0;
}