Function for Truncate and verify if a number is truncatable

problem_037/37.go

@@ -1 +1,70 @@
-package main
+package main
+
+import (
+	"strconv"
+)
+
+func BuildPrimesList(limit float64) []int {
+	primes := make([]int, 0)
+	primesCh := GetPrimes(limit)
+
+	for prime := range primesCh {
+		if prime == 0 {
+			break
+		}
+
+		primes = append(primes, prime)
+	}
+
+	return primes
+}
+
+func IsPresent(slice []int, number int) bool {
+	for _, element := range slice {
+		if element == number {
+			return true
+		}
+	}
+
+	return false
+}
+
+func Truncate(number int, from string) int {
+	digits := []int(strconv.Itoa(number))
+	length := len(digits)
+
+	if length == 1 {
+		return 0
+	}
+
+	if from == "right" {
+		digits = digits[:length - 1]
+	} else {
+		digits = digits[1:]
+	}
+
+	newNumber, _ := strconv.Atoi(string(digits))
+	return newNumber
+}
+
+func TruncateRight(number int) int {
+	return Truncate(number, "right")
+}
+
+func TruncateLeft(number int) int {
+	return Truncate(number, "left")
+}
+
+func IsTruncatable(number int, primes []int) bool {
+	operations := []string{"right", "left"}
+	for _, operation := range operations {
+		copyNumber := number
+		for copyNumber = Truncate(copyNumber, operation); copyNumber != 0; copyNumber = TruncateRight(copyNumber) {
+			if !IsPresent(primes, copyNumber) {
+				return false
+			}
+		}
+	}
+
+	return true
+}

problem_037/37_test.go

@@ -1 +1,40 @@
-package main
+package main
+
+import (
+	"testing"
+)
+
+func TestIsTruncatable(t *testing.T) {
+	primes := BuildPrimesList(3798)
+	expected := true
+	got := IsTruncatable(3797, primes)
+	if expected != got {
+		t.Errorf("Assertion error.\nExpected: %v.\nGot: %v.", expected, got)
+	}
+}
+
+func TestTruncate(t *testing.T) {
+	expected := 123
+	got := Truncate(1234, "right")
+	if expected != got {
+		t.Errorf("Assertion error.\nExpected: %v.\nGot: %v.", expected, got)
+	}
+}
+
+
+func TestTruncateRight(t *testing.T) {
+	expected := 123
+	got := TruncateRight(1234)
+	if expected != got {
+		t.Errorf("Assertion error.\nExpected: %v.\nGot: %v.", expected, got)
+	}
+}
+
+func TestTruncateLeft(t *testing.T) {
+	expected := 234
+	got := TruncateLeft(1234)
+	if expected != got {
+		t.Errorf("Assertion error.\nExpected: %v.\nGot: %v.", expected, got)
+	}
+}
+