一天一大 leet(验证回文串)难度:简单 DAY-19

入: "A man, a plan, a canal: Panama"
输出: true

输入: "race a car"
输出: false

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function (s) {
  if (!s) return true
  let _result = true,
    i = 0,
    str = s.toLowerCase().match(/[a-z0-9]/g)
  if (!str || !str.length) return true
  let len = str.length - 1
  while (i < len - i) {
    if (str[i] === str[len - i]) {
      i++
    } else {
      return (_result = false)
    }
  }
  return _result
}

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function (s) {
  var arr = s
    .replace(/[^\d^\w]/g, '')
    .toLowerCase()
    .split('')

  return arr.join() === arr.reverse().join()
}

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function (s) {
  s = s.replace(/[^0-9a-zA-Z]/g, '').toLowerCase()
  let n = s.length
  let left = 0
  let right = n - 1
  while (left < right) {
    if (s[left] != s[right]) {
      return false
    }
    left++
    right--
  }
  return true
}

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function (s) {
  if (s === '') return true
  s = s.replace(/[^a-zA-Z0-9]/g, '').toLocaleLowerCase()

  for (let i = 0, j = s.length - 1; i <= j; ) {
    if (s[i] !== s[j]) {
      return false
    }
    i++
    j--
  }
  return true
}