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Digit factorials

145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145.

Find the sum of all numbers which are equal to the sum of the factorial of their digits.

Note: as 1! = 1 and 2! = 2 are not sums they are not included.

各位数字的阶乘

145是个有趣的数，因为1! + 4! + 5! = 1 + 24 + 120 = 145。

找出所有各位数字的阶乘和等于其本身的数，并求它们的和。

注意：因为1! = 1和2! = 2不是和的形式，所以它们并不在讨论范围内。

//（Problem 34）Digit factorials
// Completed on Thu, 25 Jul 2013, 16:11
// Language: C
//
// 版权所有（C）wu yudong
// 博客地址：http://www.wuyudong.com

#include<stdio.h>
#include<math.h>
#include<stdbool.h>

int factorial(int n)			//阶乘函数
{
	if (n == 1 || n == 0)
		return 1;
	else
		return n * factorial(n - 1);
}

bool judge(int n)	//判断一个整数是否符合题意的函数
{
	char s[10];
	sprintf(s, "%d", n);
	int len = strlen(s);
	int sum = 0;
	for (int i = 0; i < len; i++) {
		sum += factorial(s[i] - '0');
	}
	if (n == sum)
		return true;
	else
		return false;
}

int main()
{
	int sum = 0;
	for (int i = 3; i < 1000000; i++) {
		if (judge(i))
			sum += i;
	}
	printf("%d\n", sum);
	return 0;
}

Answer:40730

Completed on Thu, 25 Jul 2013, 23:11