125. Verify palindrome strings

Answer:

  1. A palindrome string is a string that, when flipped, still equals itself.
  2. Take the letters and numbers from the input string (uppercase letters need to be converted to lowercase) and store them in an array.
  3. Array-basedreverseMethod to flip the string, so compare the before and after the flip.
/ * * *@param {string} s
 * @return {boolean}* /
var isPalindrome = function (s) {
  let arr = []; // Use arrays to store qualified characters

  // Iterate over s and store qualified characters into ARR
  for (const char of s) {
    // Alphanumeric characters are eligible
    if (char >= '0' && char <= '9') {
      arr.push(char);
    } else if (char >= 'a' && char <= 'z') {
      arr.push(char);
    }
    // Case should be ignored. The upper case is converted to lower case
    else if (char >= 'A' && char <= 'Z') { arr.push(char.toLowerCase()); }}// Convert the array to a string for comparison
  return arr.join(' ') === arr.reverse().join(' ');
};
Copy the code