## Problem:

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.

40730

## Code:The solution may include methods that will be found here: Library.java .

public interface EulerSolution{

public String run();

}
/*
* Solution to Project Euler problem 34
* By Nayuki Minase
*
* http://nayuki.eigenstate.org/page/project-euler-solutions
* https://github.com/nayuki/Project-Euler-solutions
*/

public final class p034 implements EulerSolution {

public static void main(String[] args) {
System.out.println(new p034().run());
}

public String run() {
// As stated in the problem, 1 = 1! and 2 = 2! are excluded.
// If a number has at least n >= 8 digits, then even if every digit is 9,
// n * 9! is still less than the number (which is at least 10^n).
int sum = 0;
for (int i = 3; i < 10000000; i++) {
if (i == factorialDigitSum(i))
sum += i;
}
return Integer.toString(sum);
}

// Hard-coded values for factorial(0), factorial(1), ..., factorial(9)
private static int[] FACTORIAL = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880};

private static int factorialDigitSum(int x) {
int sum = 0;
while (x != 0) {
sum += FACTORIAL[x % 10];
x /= 10;
}
return sum;
}

}