Leetcode Day 2: Palindrome Number Explained

The problem is as follows:
Given an integer x, return true if x is a palindrome, and false otherwise.

Example 1:

Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.
Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.
Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.

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Example 2:

Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore, it is not a palindrome.
Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore, it is not a palindrome.
Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore, it is not a palindrome.

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Example 3:

Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore, it is not a palindrome.
Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore, it is not a palindrome.
Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore, it is not a palindrome.

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Here is how I solved it:

• Let’s convert the given integer into a string
• In Python we can reverse a string by slicing: create a slice that starts at the end of the string and moves backwards. The slice statement [::-1] means start and end of the string and end at position 0, move with the step -1, which means one step backwards. https://www.w3schools.com/python/python_howto_reverse_string.asp

rev = str(x)[::-1]
rev = str(x)[::-1]
rev = str(x)[::-1]

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• Let’s compare the reversed string to the given integer (again, convert it to string: we can only compare same datatypes). Return True if it matches, else False.

if rev == str(x):
    return True
return False
if rev == str(x):
    return True
return False
if rev == str(x):
    return True
return False

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But hey, we can actually write just one line of code using ternary operator! To be honest, I am not sure if it’s bad design, but it seemed more readable to me.
Here is the complete solution:

class Solution:
    def isPalindrome(self, x: int) -> bool:
        return True if str(x)[::-1] == str(x) else False
class Solution:
    def isPalindrome(self, x: int) -> bool:
        return True if str(x)[::-1] == str(x) else False
class Solution:
    def isPalindrome(self, x: int) -> bool:
        return True if str(x)[::-1] == str(x) else False

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原文链接：Leetcode Day 2: Palindrome Number Explained