k-Multiple Free Set

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
ll S[112345];

int binary(int x, int l, int r){
    int m;
    l--;
    while(l < r-1){
        m = (l+r)/2;
        if(S[m] == x)
            return m;
        if(S[m] < x)
            l = m;
        else
            r = m;
    }
    return -1;
}

int main(){
    ll n, k;
    ll r;
    scanf("%lld %lld", &n, &k);
    int count = n;
    for(int i = 0; i < n; i++)
        scanf("%lld", &(S[i]));
    sort(S, S+n);

    for(int i = 0; i < n; i++){
        if(S[i] != 0){
            r = binary(k*S[i], i, min(n, k*S[i]));
            if(r != -1){
                S[r] = 0;
                count--;
            }
        }
    }
    printf("%d\n", count);
    return 0;
}