codeforces 274A k-Multiple Free Set

K-Multiple Free Set

Description

A k-multiple free set is a set of integers where there is no pair of integers where one is equal to another integer 
multiplied by k. That is, there are no two integers x and y(x < y) from the set, such that y = x·k.

You're given a set of n distinct positive integers. Your task is to find the size of it's largest k-multiple free subset.

Input
The first line of the input contains two integers n and k (1 ≤ n ≤ 105, 1 ≤ k ≤ 109). The next line contains a list of 
n distinct positive integers a1, a2, ..., an(1 ≤ ai ≤ 109).

All the numbers in the lines are separated by single spaces.
Output

On the only line of the output print the size of the largest k-multiple free subset of {a1, a2, ..., an}

Sample Input
Input

6 2
2 3 6 5 4 10

Output

3

Hint
In the sample input one of the possible maximum 2-multiple free subsets is {4, 5, 6}


代码：

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
long long a[100010];
int s[100010];
int main()
{
	int n,k,i;
	while(~scanf("%d%d",&n,&k))
	{
		for(i=0;i<n;i++)
		scanf("%lld",&a[i]);
		sort(a,a+n);
		memset(s,0,sizeof(s));
		int ans=n;
		for(i=0;i<n;i++)
		{
			if(s[i])
			continue;
			int l=i+1,r=n;
			long long tmp=k*a[i];
			while(r>=l)
			{
				int mid=(l+r)/2;
				if(a[mid]==tmp)
				{
					s[mid]=true;
					ans--;
					break;
				}
				else if(a[mid]>tmp)
				r=mid-1;
				else
				l=mid+1;
			}
		}
		printf("%d\n",ans);
	}
	return 0;
}