happy_number

Author: tinycedar

happy-number.go

@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+)
+
+func isHappy(n int) bool {
+	if n == 1 {
+		return true
+	}
+	m := make(map[int]bool)
+	for ; n != 1; m[n] = true {
+		sum := 0
+		for ; n > 0; n /= 10 {
+			sum += (n % 10) * (n % 10)
+		}
+		n = sum
+		if _, ok := m[n]; ok {
+			return false
+		}
+	}
+	return true
+}
+
+func main() {
+	fmt.Println(isHappy(7))
+}