05 valid-palindromehttps://leetcode.com/problems/valid-palin

整理成需要的形式，例如： 'aabbcc'
倒序循环直接拼接，注意终止条件是 i >= 0

/**
 * @param {string} s
 * @return {boolean}
 */
var isPalindrome = function(s) {
    const cleanStr = s.toLocaleLowerCase().replace(/[\W_]/g, '')
    let str = ''
    for(let i = cleanStr.length - 1;i >= 0;i--) {
        str += cleanStr[i]
    }
    return str === cleanStr
};