92: Square digit chains

92_square_digit_chains/main.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+)
+
+func main() {
+	count := 0
+	for i := 1; i < 10000000; i++ {
+		if goChain(i) {
+			count++
+		}
+	}
+	fmt.Println(count)
+}
+
+func goChain(n int) bool {
+	s := strconv.Itoa(n)
+	sum := 0
+	for _, c := range s {
+		i, _ := strconv.Atoi(string(c))
+		sum += i * i
+	}
+	if sum == 89 {
+		return true
+	} else if sum == 1 {
+		return false
+	}
+	return goChain(sum)
+}

92_square_digit_chains/main_test.go

@@ -0,0 +1,32 @@
+package main
+
+import "testing"
+
+func Test_goChain(t *testing.T) {
+	type args struct {
+		n int
+	}
+	tests := []struct {
+		name string
+		args args
+		want bool
+	}{
+		{
+			"test1",
+			args{44},
+			false,
+		},
+		{
+			"test2",
+			args{85},
+			true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := goChain(tt.args.n); got != tt.want {
+				t.Errorf("goChain() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}