valid-palindrome solution

Author: ohgyulim

valid-palindrome/ohgyulim.java

@@ -0,0 +1,21 @@
+class Solution {
+    public boolean isPalindrome(String s) {
+        StringBuilder sb = new StringBuilder();
+
+        for (char ch : s.toCharArray()) {
+            if (Character.isLetterOrDigit(ch)) {
+                sb.append(Character.toLowerCase(ch));
+            }
+        }
+
+        for (int i = 0; i < sb.length(); i++) {
+            int left = i;
+            int right = sb.length() - i - 1;
+
+            if (left >= right) return true;
+            if (sb.charAt(left) != sb.charAt(right)) return false;
+        }
+
+        return true;
+    }
+}