CodeForces 460B Little Dima and Equation 枚举

---

title: CodeForces 460B Little Dima and Equation 枚举
date: 2016-08-03 19:33:29
tags:
- 枚举
- CodeForces

Little Dima and Equation
题意：
给出a,b,c,求满足x = b·s(x)^a + c的x有哪些。
s(x)是x每一位之和

思路：
由于x不超过1e9，所以s(x)最大是81，枚举1到81计算s(x)是否相等即可

#include<bits/stdc++.h>
using namespace std;
const long long MAXN = 1e9;
long long ans[10000000];
long long s(long long x)
{
	long long d = 0; 
	while(x)
	{
		d += x%10;
		x /= 10;
	}
	return d;
}

int main(int argc, char const *argv[])
{
	long long a, b, c;
    //freopen("in.txt", "r", stdin); 
	while(~scanf("%I64d%I64d%I64d", &a, &b, &c))
	{
		memset(ans, 0, sizeof(ans));
		long long cnt = 0;
		for (long long i = 1; i<=81; ++i)
		{
			long long x = 1;
			for (long long j = 0; j < a; ++j)
			{
				x*=i;
			}
			//printf("i=%d %d
", i,  b*x+c);
			if(s(b*x+c) == i&&(b*x+c>0)&&(b*x+c<MAXN))
			{
				ans[cnt++] = b*x+c;
			}
		}
		printf("%I64d
", cnt);
		if(cnt)
		{
			for (int i = 0; i < cnt-1; ++i)
			{
				printf("%I64d ", ans[i]);
			}
			printf("%I64d
", ans[cnt-1]);
		}
	}
	return 0;
}