JavaScript find valid palindrome or not | leet code question 125

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 If you come here to check the solution of the following question. 

 JavaScript find valid palindrome or not

this question is asked in LeetCode as a valid palindrome(Question Number -125) and its difficulty is easy.

If you search on google mostly we get solutions in Java, Python, or C++. if we are lucky then only we get the solution in javascript for the leet code questions.

So let's first understand the question.

A phrase is a palindrome if it reads the same forward and backward after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters. 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 * 105
• s consists only of printable ASCII characters.

So the solution to the above question is.

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function(s) {

    s = s.toLowerCase().replace(/[\W_]/g,""); 	// replace() method will replace all non alphanumeric to empty chars
    let left = 0;
    let right = s.length-1;
    while(left < right){
        if(s[left]!==s[right]){
            return false;
        }
        left++;
        right--;
        
    }
    return true;
    
};

Complexity of the solution is as follows:

Time Complexity: O(N)

Space Complexity: O(1)