hdu 4430——Yukari's Birthday

二分+枚舉

二分寫的好挫

#include<stdio.h>
#include<math.h>
#include<iostream>
using namespace std;
#define LL __int64
#define INF ((LL)1<<60)
LL n,ans;
LL a,b;
LL fun(LL bi,LL r)
{
	LL k=1;
	LL tmp=0;
	while(r--)
	{
		k*=bi;
		tmp+=k;	
	}	
	return tmp;
}
void get(int len)
{
	LL l=1,r=(LL)pow((double)n,1.0/len);//l=1 因爲我挫的二分查找寫法 
	if(r<2)//注意點 
		r=2;
	LL mid;
	LL tmp;
	while(l<r-1)
	{
		mid=(l+r)/2;
		LL tmp=fun(mid,len);
		if(tmp>=n-1)
			r=mid;
		else
			l=mid;
	}
	tmp=fun(r,len);
	if(tmp==n-1||tmp==n)
	{
		if(ans>len*r)
		{
			ans=len*r;
			a=len;
			b=r;
		}
	}
}
int main()
{
	while(cin>>n)	
	{
		ans=INF;
		a=b=1;
		for(int len=2;len<=45;len++)
			get(len);
		if(ans!=INF)
			cout<<a<<" "<<b<<endl;	
		else
			cout<<1<<" "<<n-1<<endl;
	}
	return 0;
}