HackerEarth Vegetable Market problem solution

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define si(x) scanf("%d", &x)
#define sc(x) scanf("%c", &x)
#define sl(x) scanf("%lld", &x)
#define pl(x) printf("%lldn", x)
#define pi(x) printf("%dn", x)
#define gu getchar_unlocked
#define pu putchar_unlocked
#define setbits __builtin_popcountll
#define pb push_back
#define mp make_pair
#define MOD 1000000007
#define speed ios::sync_with_stdio(false)

ll arr[100005];
ll leftarr[1000005], rightarr[1000005];
vector <ll> quan(1000005, 0);

int main(){
  int n, i;
  si(n);
  for(i = 1; i <= n; i++){
    sl(arr[i]);
    leftarr[arr[i]]++;
    rightarr[arr[i]]++;
  }
  for(i = 1; i <= 1000002; i++){
    leftarr[i] = leftarr[i - 1] + (i * leftarr[i]);
  }
  for(i = 1000002; i >= 0; i--){
    rightarr[i] += rightarr[i + 1];
  }
  for(i = 1; i <= 1000002; i++){
    quan[i] = leftarr[i - 1] + (rightarr[i] * i);
  }
  int q;
  si(q);
  while(q--){
    ll K;
    sl(K);
    vector <ll> :: iterator it;
    it = lower_bound(quan.begin(), quan.end(), K);
    if(it != quan.end()){
      int index = it - quan.begin();
      pi(index);
    }
    else{
      pi(-1);
    }
  }
}