题解 | #请客吃饭#

#include <iostream>
#include <queue>
#include <map>
#include <set>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <iomanip>
#include <stack>
#include <numeric>
#include <ctime>
#include <string>
#include <bitset>
#include <unordered_map>
#include <unordered_set>

using namespace std;
using ll = long long;

const ll N = 2e5 + 5, mod = 1e9 + 7, inf = 0x3f3f3f3f;

pair<ll, ll>a[N];
ll n, k;

bool check(ll mid) {
    ll maxx = -inf, minn = inf, sum = 0;

    queue<pair<ll, ll>>q;

    for (int i = 1; i <= n; i++) {
        ll x = a[i].first, y = a[i].second;

        q.push(a[i]);
        sum += y;

        while (!q.empty() && q.front().first < x - mid) {
            sum -= q.front().second;
            q.pop();
        }

        maxx = max(maxx, sum);

    }

    return maxx >= k;

}

void solve() {
    cin >> n >> k;

    for (int i = 1; i <= n; i++) {
        cin >> a[i].first;
    }
    for (int i = 1; i <= n; i++) {
        cin >> a[i].second;
    }

    sort(a + 1, a + 1 + n);

    ll l = 0, r = 1e12;
    ll ans = 2e18;
    while (l <= r) {
        ll mid = l + r >> 1;

        if (check(mid)) {
            r = mid - 1;
            ans = mid;
        } else {
            l = mid + 1;
        }
    }

    cout << (ans == 2e18 ? -1 : ans);
}

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

    int t = 1;
    //cin >> t;

    while (t--) {
        solve();
    }

    return 0;
}