PAT_1085. Perfect Sequence

#include <iostream>#include <algorithm>using namespace std;long long int a[100005],b[100005];int N,p;int binarySearch(int left,long long int m){int mid,right=N-1;while(left<=right){mid=(left+right)/2;if(a[mid]<m)left=mid+1;else if(a[mid]>m)right=mid-1;elsereturn mid;}return left;}int main(){scanf("%d%d",&N,&p);for(int i=0;i<N;i++)scanf("%lld",&a[i]);sort(a,a+N);for(int i=0;i<N;i++)b[i]=a[i]*p;int maxNum=0;for(int j=0;j<N;j++){int i=binarySearch(j,b[j]);if(a[N-1]<=b[j]&&N-j>maxNum)maxNum=N-j;else if(i-j>maxNum)maxNum=i-j;}cout<<maxNum<<endl;return 0;}