Job Scheduling / SPOJ-Milk Scheduling Solution

/*    problem link:
      https://www.spoj.com/problems/MSCHED/en/    */

#include<bits/stdc++.h>
#define endl  "\n"
#define ll long long
#define PI acos(-1.0)
#define test cout<<"\n****\n"
#define precise fixed(cout);cout<<setprecision(12)
#define fast  ios_base :: sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
using  namespace  std;

vector<pair<ll,ll>> vec;
int main(){

    fast;
    ll n;
    cin>>n;

    for(ll i=0;i<n;i++){
        ll g,d;
        cin>>g>>d;
        vec.push_back(make_pair(g,d));
    }
    sort(vec.rbegin(),vec.rend());

    bool slot[n];
    memset(slot, false,sizeof(slot));

    ll sum = 0;
    for (int i=0; i<n; i++)
    {
        for (int j=min(n, vec[i].second)-1; j>=0; j--)
        {
            if (slot[j]==false)
            {
                sum = sum + vec[i].first;
                slot[j] = true;
                break;
            }
        }
    }
    cout<<sum;

    return 0;
}