A_Helmets_in_Night_Light.cpp

#include <bits/stdc++.h>
#define int long long
#define ab adityabelgaonkar
using namespace std;

bool customComp(pair<int, int> a, pair<int, int> b)
{
    if(a.first == b.first) return a.second > b.second;
    return a.first < b.first;
}

int32_t main()
{
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    
    int t; cin >> t;
    while(t--)
    {
        int n, p; cin >> n >> p;
        vector<pair<int, int>> a(n);
        
        for(auto &i : a) cin >> i.second;
        for(auto &i : a) cin >> i.first;

        sort(a.begin(), a.end(), customComp);

        //i.second is number of people we can tell for cost of i.first
        // for(auto &i : a) cout << i.second << ' '; cout << '\n';
        // for(auto &i : a) cout << i.first << ' '; cout << '\n';

        int ans = p;
        int unlocked = 1;

        for(int i = 0; i < n; ++i)
        {
            if(a[i].first > p || unlocked >= n) break;
            if(n - unlocked < a[i].second)
            {
                ans += a[i].first * (n - unlocked);
            }
            else
            {
                ans += a[i].first * a[i].second;
            }

            unlocked += a[i].second;
        }

        ans += p * max(0ll, n - unlocked);

        cout << ans << '\n';
    }

    return 0;
}