Merge pull request neetcode-gh#432 from vorenusCoA/main

Updating 125-valid-Palindrome.java so it uses two pointers

Author: neetcode-gh

java/125-Valid-Palindrome.java

@@ -1,9 +1,29 @@
 public boolean isPalindrome(String s) {
-        StringBuilder content = new StringBuilder();
-        for(int i = 0; i < s.length(); i++) 
-            if(Character.isLetterOrDigit(s.charAt(i)))
-                content.append(s.charAt(i));
-        content = new StringBuilder(content.toString().toLowerCase());
-        String value = content.toString();
-        return value.equals(content.reverse().toString());
+        
+    int i = 0;
+    int j = s.length() - 1;
+    while (i < j) {
+        
+        Character start = s.charAt(i);
+        Character end = s.charAt(j);
+        
+        if (!Character.isLetterOrDigit(start)) {
+            i++;
+            continue;
+        }
+        
+        if (!Character.isLetterOrDigit(end)) {
+            j--;
+            continue;
+        }
+        
+        if (Character.toLowerCase(start) != Character.toLowerCase(end)) {
+            return false;
+        }
+        
+        i++;
+        j--;    
     }
+    
+    return true;
+}