solves valid palindrome

Author: anishLearnsToCode

README.md

@@ -43,8 +43,8 @@
 | 118 | [Pascal's Triangle](https://leetcode.com/problems/pascals-triangle) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/PascalsTriangle.java) | 
 | 119 | [Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/PascalsTriangleII.java) | 
 | 121 | [Best Time to Buy and Sell Stocks](https://leetcode.com/problems/best-time-to-buy-and-sell-stock) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/BestTimeToBuyAndSellStock.java) |
-| 122 | [Best Time to Buy and Sell Stocks II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii) | Easy |
-| 125 | [Valid Palindrome](https://leetcode.com/problems/valid-palindrome) | Easy |
+| 122 | [Best Time to Buy and Sell Stocks II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](https://github.com/anishLearnsToCode/leetcode-algorithms/blob/master/src/BestTimeToBuyAndSellStockII.java) | 
+| 125 | [Valid Palindrome](https://leetcode.com/problems/valid-palindrome) | Easy | 
 | 136 | [Single Number](https://leetcode.com/problems/single-number) | Easy |
 | 141 | [Linked List Cycle](https://leetcode.com/problems/linked-list-cycle) | Easy |
 | 155 | [Min Stack](https://leetcode.com/problems/min-stack) | Easy |

src/ValidPalindrome.java

@@ -0,0 +1,22 @@
+public class ValidPalindrome {
+    public boolean isPalindrome(String string) {
+        final StringBuilder alphanumeric = toAlphaNumeric(string);
+        for (int index = 0 ; index < alphanumeric.length() / 2 ; index++) {
+            if (alphanumeric.charAt(index) != alphanumeric.charAt(alphanumeric.length() - index - 1)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    private static StringBuilder toAlphaNumeric(String string) {
+        StringBuilder result = new StringBuilder();
+        for (int index = 0 ; index < string.length() ; index++) {
+            char character = string.charAt(index);
+            if (Character.isAlphabetic(character) || Character.isDigit(character)) {
+               result.append(Character.toLowerCase(character));
+            }
+        }
+        return result;
+    }
+}