valid palindrome solution

Author: Jeongwon Na

valid-palindrome/njngwn.java

@@ -0,0 +1,22 @@
+class Solution {
+    public boolean isPalindrome(String s) {
+        s = s.toLowerCase();    // convert into lowercase letters
+        s = s.replaceAll("[^a-zA-Z0-9]", "");  // remove non-alphanumeric characters
+        int start = 0;
+        int end = s.length()-1;
+
+        while (start < end) {
+            char startChar = s.charAt(start);
+            char endChar = s.charAt(end);
+
+            if (startChar != endChar) {
+                return false;
+            }
+
+            ++start;
+            --end;
+        }
+
+        return true;
+    }
+}