Codeforces Round #494 (Div. 3), problem: (D) Coins and Queries

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define pii pair<int,int>
#define pli pair<long long int,int>
#define pbi pair<bool,int>
#define pob pop_back
#define all(a) a.begin(),a.end()
#define fio ios_base::sync_with_stdio(false); cin.tie(0);cout.tie(0);
#define i64 long long int
#define mem(x,y) memset(x,y,sizeof(x))
#define fill(arr,b) fill(arr, arr+sizeof(arr)/sizeof(arr[0]), b)
#define maxarr(n,arr,m) m =-1e9;for(int i=0;i<n;i++)if(arr[i]>m) m=arr[i];

const double pi = acos(-1.0);
const int maxn = (i64)2e9+5;

map <int,int> mp;
int arr[200005];
int main()
{
    //freopen("input.txt","r",stdin);
    int n,q,b,a,k=0;
    scanf("%d%d",&n,&q);
    for(int i = 0 ; i<n ; i++)
    {
        scanf("%d",&a);
        if(mp[a]==0) arr[k++]=a;
        mp[a]++;
    }
    n=k;
    sort(arr,arr+n,greater<int>());

    while(q--)
    {
        scanf("%d",&b);
        int cnt = 0;
        for(int i = 0 ; i<n ; i++)
        {
            if(b<arr[i]) continue;
            else if(b/arr[i] <= mp[arr[i]])
            {
                cnt += b/arr[i];
                b = b%arr[i];
            }
            else
            {
                b -= mp[arr[i]]*arr[i];
                cnt += mp[arr[i]];
            }
            if(b==0) break;
        }
        if(b==0) printf("%d\n",cnt);
        else printf("-1\n");
    }
    return 0;
}