leetcode:Valid Palindrome【Python版】

1、注意空字符串的处理；

2、注意是alphanumeric字符；

3、字符串添加字符直接用+就可以；

class Solution:
    # @param s, a string
    # @return a boolean
    def isPalindrome(self, s):
        ret = False
        s = s.lower()
        ss = ""
        for i in s:
            if i.isalnum():
                ss += i
        h = 0
        e = len(ss)-1
        while(h<e):
            if(ss[h] == ss[e]):
                h += 1
                e -= 1
            else:
                break
        if h>=e:
            ret = True
        return ret