牛客9-Happy Number

传送门

#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
#include<map>
#include<queue>
#include<math.h>
#include<vector>
using namespace std;
#define ll long long
ll a[1000];

int main()
{
    
    
	ll n;
	cin>>n;
	ll k = 0;
	if(n == 1)
	{
    
    
		cout<<2;
		return 0;
	}
	while(n > 0)
	{
    
    
		n-=pow(3,k);
		k++;
		if(n < pow(3,k))break;
	}
	int num = 0;
	while(n > 0)
	{
    
    
		a[num] = (n%3);
		n /= 3;
		num++;
	}
	
	for(int i = k-1;i >= 0 ;i--)
	if(a[i] == 0)cout<<2;
	else if(a[i] == 1)cout<<3;
	else cout<<6;
}