feat(work): add valid-palindrome solution for easy difficulty

work/Easy/Two Pointers/125.valid-palindrome.js

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+/*
+ * 125. Valid Palindrome
+ * Difficulty: Easy
+ * https://leetcode.com/problems/valid-palindrome/
+ * 
+ * ──────────────────────────────────────────────────
+ * 
+ * A phrase is a palindrome if, after converting all uppercase letters
+ * into lowercase letters and removing all non-alphanumeric characters,
+ * it reads the same forward and backward. Alphanumeric characters
+ * include letters and numbers.
+ * 
+ * Given a string s, return true if it is a palindrome, or false
+ * otherwise.
+ * 
+ *  
+ * 
+ * Example 1:
+ * 
+ * Input: s = "A man, a plan, a canal: Panama"
+ * Output: true
+ * Explanation: "amanaplanacanalpanama" is a palindrome.
+ * 
+ * Example 2:
+ * 
+ * Input: s = "race a car"
+ * Output: false
+ * Explanation: "raceacar" is not a palindrome.
+ * 
+ * Example 3:
+ * 
+ * Input: s = " "
+ * Output: true
+ * Explanation: s is an empty string "" after removing non-alphanumeric
+ * characters.
+ * Since an empty string reads the same forward and backward, it is a
+ * palindrome.
+ * 
+ *  
+ * 
+ * Constraints:
+ * 
+ * 	• 1 <= s.length <= 2 * 10^5
+ * 
+ * 	• s consists only of printable ASCII characters.
+*/
+
+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var isPalindrome = function(s) {
+  let normal = s.replace(/[^a-zA-Z0-9]/g, "").toLowerCase()    
+  let i = 0, j = normal.length - 1;
+
+  while (i < j) {
+    if(normal[i] !== normal[j]) {
+      return false;
+    }
+    i++;
+    j--;
+  }
+  return true;
+};