（Problem 34）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.

 

题目大意：

145 是一个奇怪的数字, 因为 1! + 4! + 5! = 1 + 24 + 120 = 145.

找出所有等于各位数字阶乘之和的数字之和。

注意: 因为 1! = 1 和 2! = 2 不是和的形式，所以它们不算在内。

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<ctype.h>
#include<stdlib.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