34: digit factorials

34_digit_factorials/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func main() {
+	sum := 0
+	max := factorialOf(9) * 10
+	for i := 3; i < max; i++ {
+		if sumNumberFactorials(splitNumber(i)) == i {
+			sum += i
+		}
+	}
+	fmt.Println("sum:", sum)
+}
+
+func sumNumberFactorials(ns []int) int {
+	sum := 0
+	for _, n := range ns {
+		sum += factorialOf(n)
+	}
+	return sum
+}
+
+func splitNumber(n int) []int {
+	var ret []int
+	str := strconv.Itoa(n)
+	for _, c := range str {
+		i, _ := strconv.Atoi(string(c))
+		ret = append(ret, i)
+	}
+	return ret
+}
+
+func factorialOf(n int) int {
+	p := 1
+	for i := n; i > 0; i-- {
+		p *= i
+	}
+	return p
+}