Add recursive method for palindrome (TheAlgorithms#455)

Author: nischal20

strings/palindrome/ispalindrome.go

@@ -35,3 +35,21 @@ func IsPalindrome(text string) bool {
 	}
 	return true
 }
+
+func IsPalindromeRecursive(text string) bool {
+	clean_text := cleanString(text)
+	runes := []rune(clean_text)
+	return isPalindromeRecursiveHelper(runes, 0, int64(len(runes)))
+}
+
+func isPalindromeRecursiveHelper(runes []rune, start int64, end int64) bool {
+	if start >= end {
+		return true
+	}
+	if runes[start] != runes[end-1] {
+		return false
+	}
+	start = start + 1
+	end = end - 1
+	return isPalindromeRecursiveHelper(runes, start, end)
+}

strings/palindrome/ispalindrome_test.go

@@ -51,3 +51,14 @@ func TestIsPalindrome(t *testing.T) {
 		})
 	}
 }
+
+func TestIsPalindromeRecursive(t *testing.T) {
+	for _, test := range testCases {
+		t.Run(test.name, func(t *testing.T) {
+			func_result := IsPalindromeRecursive(test.input)
+			if test.expected != func_result {
+				t.Errorf("Expected answer '%t' for string '%s' but answer given was %t", test.expected, test.input, func_result)
+			}
+		})
+	}
+}