PATA1085题解

二分查找法

//
//  main.cpp
//  PATA1085
//
//  Created by Phoenix on 2018/1/7.
//  Copyright © 2018年 Phoenix. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

int binarySearch(int A[],int left,int right,long long x){
    int mid;
    while(left<right){
        mid=(left+right)/2;
        if(A[mid]>x){
            right=mid;
        }else{
            left=mid+1;
        }
    }
    return left;
}

int main(int argc, const char * argv[]) {
    int n,p;
    scanf("%d %d",&n,&p);
    int a[100010];
    for(int i=0;i<n;i++){
        scanf("%d",&a[i]);
    }
    sort(a,a+n);
    int max=1;
    for(int i=0;i<n;i++){
        //long long t=a[i]*p;
        int m=binarySearch(a,i+1,n,(long long)a[i]*p);
        if(m-i>max) max=m-i;
    }
    /*for(int i=0;i<n;i++){
        int j=upper_bound(a+i+1, a+n, (long long)a[i]*p)-a;
        if(j-i>max) max=j-i;
    }*/
    printf("%d\n",max);
    return 0;
}