Merge pull request #914 from skmodi649/Add-Palindrome.java

Add palindrome.java

Java/Data-Structures/String/Palindrome.java

@@ -0,0 +1,66 @@
+// This code will check for palindrome strings
+
+/** Palindrome String : A string that is spelt same even if reversed is called palindrome string.
+ * example : madam , civic , kayak , refer , reviver etc.
+ *
+ * Algorithm for checking palindrome strings :
+ * 1. Take a string as input
+ * 2. Convert all the characters to lower case
+ * 3. Reverse the string
+ * 4. Now check if the reversed string and original strings are equal using 'equals()' method or simply '==' sign
+ * 5. If equal then print "Palindrome" else print "Not Palindrome"
+ */
+
+
+import java.util.Scanner;
+public class Palindrome
+{
+    public static void main(String []args)
+    {
+        // Using Scanner class to take input form the user
+        Scanner sc = new Scanner(System.in);
+
+        System.out.println("Enter the string : ");
+
+        // .next() method is used for taking a single string as input in java Scanner class
+        String word = sc.next();
+
+        // using .toLowerCase() method to convert the string to lower case
+        String lowerword = word.toLowerCase();
+
+        //Now lowerword contains the lowercase form of the string word
+
+        String reverse = "";     // String to store the reverse
+
+        // Reversing the string using for loop that runs from string.length()-1 to 0
+        for(int i = lowerword.length()-1;i>=0;i--)
+        {
+            char ch = lowerword.charAt(i);
+            reverse = reverse + ch;
+        }
+
+        // Now lets check for the equality of the string and its reverse
+
+        if(lowerword.equals(reverse))
+            System.out.println("Palindrome");
+        else
+            System.out.println("Not Palindrome");
+    }
+}
+
+
+
+/** TEST CASES
+ * Test Case 1 :
+ * Input : Madam
+ * Output : Palindrome
+ *
+ * Test Case 2 :
+ * Input : acquire
+ * Output : Not Palindrome
+ */
+
+/**
+ * Time Complexity : O(length of word)
+ * Auxiliary Space Complexity : O(1)
+ */