refactor(strings): is palindrome

.sdkmanrc

@@ -1,3 +1,3 @@
 # Enable auto-env through the sdkman_auto_env config
 # Add key=value pairs of SDKs to use below
-java=16.0.0-zulu
+java=23.0.1-zulu

buildSrc/src/main/kotlin/Versions.kt

@@ -1,7 +1,7 @@
 object Versions {
     const val PROJECT = "2.1.1"
     const val KOTLIN = "2.1.0"
-    const val GRADLE = "6.8.3"
+    const val GRADLE = "8.11.1"
 
     const val DETEKT = "1.9.1"
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

ktstrings/src/main/kotlin/com/kotlinground/strings/palindromes/isPalindrome.kt

@@ -10,11 +10,20 @@ fun isPalindrome(s: String): Boolean {
     var right = s.length - 1
 
     while (left < right) {
-        if (s[left] != s[right]) {
+        while (left < right && !s[left].isLetterOrDigit()) {
+            left++
+        }
+        while (left < right && !s[right].isLetterOrDigit()) {
+            right--
+        }
+
+        if (s[left].lowercase() != s[right].lowercase()) {
             return false
         }
+
         left++
         right--
     }
+
     return true
 }

ktstrings/src/test/kotlin/com/kotlinground/strings/palindromes/IsPalindromeTest.kt

@@ -0,0 +1,65 @@
+package com.kotlinground.strings.palindromes
+
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class IsPalindromeTest {
+
+ @Test
+ fun `should return true for anna`() {
+  val s = "anna"
+  val actual = isPalindrome(s)
+  assertTrue(actual)
+ }
+
+ @Test
+ fun `should return false for walter`() {
+  val s = "walter"
+  val actual = isPalindrome(s)
+  assertFalse(actual)
+ }
+
+ @Test
+ fun `should return true for 12321`() {
+  val s = "12321"
+  val actual = isPalindrome(s)
+  assertTrue(actual)
+ }
+
+ @Test
+ fun `should return false for 123456`() {
+  val s = "123456"
+  val actual = isPalindrome(s)
+  assertFalse(actual)
+ }
+
+ @Test
+ fun `should return true for Was it a cat I saw`() {
+  val s = "Was it a cat I saw?"
+  val actual = isPalindrome(s)
+  assertTrue(actual)
+ }
+
+ @Test
+ fun `should return true for Never odd or even`() {
+  val s = "Never odd or even"
+  val actual = isPalindrome(s)
+  assertTrue(actual)
+ }
+
+ @Test
+ fun `should return true for radar`() {
+  val s = "radar"
+  val actual = isPalindrome(s)
+  assertTrue(actual)
+ }
+
+ @Test
+ fun `should return true for Live on time, emit no evil`() {
+  val s = "Live on time, emit no evil"
+  val actual = isPalindrome(s)
+  assertTrue(actual)
+ }
+
+}