problem address
Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward. Example 1: Input: 121 Output: true Example 2: Input: -121 Output: false Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome. Example 3: Input: 10 Output: false Explanation: Reads 01 from right to left. Therefore it is not a palindrome. Follow up: Coud you solve it without converting the integer to a string?前面了两种方法是取巧了，另外不用转化成字符串怎么做？ 可以将数字每位上取出来然后再进行比较
class Solution: def isPalindrome(self, x: int) -> bool: # return list(str(x)) == list(reversed(str(x))) # return str(x) == str(x)[::-1] if x < 0: return False beg = 0 s = str(x) beg, end = 0, len(s) - 1 while beg < end: if s[beg] == s[end]: beg += 1 end -= 1 else: return False return True class Solution: def isPalindrome(self, x: int) -> bool: if x < 0: return False elif x == 0: return True l = [] while x != 0: l.append(x%10) x = x // 10 return l == list(reversed(l))