TheAlgorithms · yanglbme · Aug 28, 2019 · Aug 28, 2019 · Aug 28, 2019
@@ -16,6 +16,7 @@ public static void main(String[] args) {
         String str = input.nextLine();
 
         System.out.println("Your text has " + wordCount(str) + " word(s)");
+        System.out.println("Your text has " + secondaryWordCount(str) + " word(s)");
         input.close();
     }
 
@@ -25,4 +26,25 @@ private static int wordCount(String s) {
         return s.trim().split("[\\s]+").length;
     }
 
+    /**
+     * counts the number of words in a sentence but ignores all potential
+     * non-alphanumeric characters that do not represent a word. runs in O(n) where
+     * n is the length of s
+     * 
+     * @param s String: sentence with word(s)
+     * @return int: number of words
+     */
+    private static int secondaryWordCount(String s) {
+        if (s == null || s.isEmpty())
+            return 0;
+        StringBuilder sb = new StringBuilder();
+        for (char c : s.toCharArray()) {
+            if (Character.isLetter(c) || Character.isDigit(c))
+                sb.append(c);
+        }
+        s = sb.toString();
+        return s.trim().split("[\\s]+").length;
+
+    }
+
 }
@@ -22,4 +22,29 @@ public boolean SecondWay(String x) {
 
         return SecondWay(x.substring(1, x.length() - 1));
     }
+
+    /**
+     * This method ignores all non-alphanumeric characters and case runs in O(n)
+     * where n is the length of s
+     * 
+     * @param s String to check
+     * @return true if s is palindrome else false
+     */
+    public boolean isPalindrome(String s) {
+        s = s.toLowerCase().trim();
+        StringBuilder sb = new StringBuilder();
+        for (char c : s.toCharArray()) {
+            if (Character.isLetter(c) || Character.isDigit(c))
+                sb.append(c);
+        }
+        s = sb.toString();
+        int start = 0;
+        int end = s.length() - 1;
+        while (start <= end) {
+            if (s.charAt(start++) != s.charAt(end--))
+                return false;
+
+        }
+        return true;
+    }
 }