（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。

//（Problem 34）Digit factorials

// Completed on Thu, 25 Jul 2013, 16:11

// Language: C

//

// 版权所有（C）acutus   (mail: [email protected]) 

// 博客地址：http://www.cnblogs.com/acutus/

#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