问题标题: 酷町堂：5098

#include<iostream>
#include<cstring>
#include<cmath>
#include<string>
#include<cstdio>
using namespace std;
int a[40005],f[40005],d,n,x;
int dfs(int i){
    if(f[i]!=-1)return f[i];
    int mx=-1;
    for(int j=1;j<=i-1;j++){
        if(a[j]/a[i]==d)
            mx=max(mx,dfs(j));
    }
    if(mx==-1){
        f[i]=1;
        return 1;
    }
    else{
        f[i]=mx+1;
        return mx+1;
    }
}
int main()
{
    memset(f,-1,sizeof(f));
    int mxz=-1;
    cin>>n>>d;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    for(int i=1;i<=n;i++)
        mxz=max(mxz,dfs(i));
    cout<<mxz;
    return 0;
}

60分