Leetcode: Strobogrammatic Number

最新推荐文章于 2021-06-08 03:27:18 发布

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本文介绍了一个Python函数，用于判断一个字符串形式的数字是否为旋转对称数（即倒置180度后仍与原数相同）。例如，“69”、“88”和“818”都是旋转对称数。

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Question

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down).

Write a function to determine if a number is strobogrammatic. The number is represented as a string.

For example, the numbers “69”, “88”, and “818” are all strobogrammatic.

Hide Tags Hash Table Math
Hide Similar Problems (M) Strobogrammatic Number II (H) Strobogrammatic Number III

My Solution

“`python
class Solution(object):
def isStrobogrammatic(self, num):
“””
:type num: str
:rtype: bool
“”“

    if num==None or num=='':
        return False

    start, end = 0, len(num)-1
    while start<=end:
        if not self.check(num, start, end):
            return False
        start += 1
        end -= 1

    return True

def check(self, num, i, j):
    if i==j:
        if num[i] in ['0','1','8']:
            return True
    else:
        if num[i]==num[j] and num[i] in ['0','1','8']:
            return True
        if (num[i],num[j])==('6','9') or (num[i],num[j])==('9','6'):
            return True

    return False

“`