Gym 101194D Ice Cream Tower

被一道数位DP折磨得欲仙欲死之后，再做这道题真是如同吃了ice cream一样舒畅啊

#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define ms(arr,a) memset(arr,a,sizeof arr)
#define debug(x) cout<<"< "#x" = "<<x<<" >"<<endl
typedef long long ll;
const int maxn=3e5+5;
ll a[maxn],b[maxn];
int n,k;
bool ok(int m)
{
    ms(b,0);
    int cnt=1;
    for(int i=1;i<=k;++i)
    for(int j=1;j<=m;++j)
    {
        if(cnt>n)return false;
        while(a[cnt]<2*b[j]){cnt++;if(cnt>n)return false;}
        b[j]=a[cnt++];
    }
    return true;
}
int main()
{
    freopen("Input.txt","r",stdin);
    freopen("1.txt","w",stdout);
    int T;scanf("%d",&T);
    for(int Case=1;Case<=T;Case++)
    {
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;++i)scanf("%lld",a+i);
	sort(a+1,a+n+1);
	int l=0,m,r=n/k;
    while(l<r)
    {
        m=(l+r+1)/2;
        if(ok(m))l=m;
        else r=m-1;
    }
    printf("Case #%d: %d
",Case,l);//
    }
    //freopen("CON","w",stdout);
    //system("start Output.txt");
}