[Java] : Adding Stack approach to check a string is palindrome or not

src/main/java/string/PalindromCheckSnippet.java

@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2017-2022 Ilkka Seppälä
+ * Copyright (c) 2017-2024 Ilkka Seppälä
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,6 +24,9 @@
 
 package string;
 
+import java.util.ArrayDeque;
+import java.util.Deque;
+
 /**
  * PalindromCheckSnippet.
  */
@@ -52,4 +55,22 @@ public static boolean isPalindrome(String s) {
 
     return true;
   }
+
+  /**
+   * Break the string into character array and keep iterating the stack. Then,
+   * While the stack is not empty and keep storing the popped elements into a StringBuilder
+   */
+  public static boolean isPalindromeWithStack(String s) {
+    Deque<Character> st = new ArrayDeque<>();
+    char[] c = s.toCharArray();
+    for (char c1 : c) {
+      st.push(c1);
+    }
+    StringBuilder sb = new StringBuilder();
+    while (!st.isEmpty()) {
+      sb.append(st.pop());
+    }
+    return sb.toString().equals(s);
+  }
+
 }

src/test/java/string/PalindromCheckSnippetTest.java

@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2017-2022 Ilkka Seppälä
+ * Copyright (c) 2017-2024 Ilkka Seppälä
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -45,4 +45,13 @@ void testIsPalindrome() {
     assertFalse(PalindromCheckSnippet.isPalindrome("Type O Negative"));
     assertFalse(PalindromCheckSnippet.isPalindrome("Foo12121Bar"));
   }
-}
+
+  @Test
+  void testIsPalindromeWithStack() {
+    assertTrue(PalindromCheckSnippet.isPalindromeWithStack("madam"));
+    assertTrue(PalindromCheckSnippet.isPalindromeWithStack("eye"));
+    assertTrue(PalindromCheckSnippet.isPalindromeWithStack("abbbdddbbba"));
+    assertFalse(PalindromCheckSnippet.isPalindromeWithStack("abbbca"));
+    assertFalse(PalindromCheckSnippet.isPalindromeWithStack("logic"));
+  }
+}