DAY 26
0

# 9. Palindrome Number

## Question

Given an integer `x`, return true if `x` is palindrome integer.

An integer is a palindrome when it reads the same backward as forward. For example, `121` is palindrome while `123` is not.

## Example

### Example1

``````Input: x = 121
Output: true
``````

### Example2

``````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.
``````

### Example3

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

### Example 4:

``````Input: x = -101
Output: false
``````

### Constraints

• `-2^31 <= x <= 2^31 - 1`

## 解題

### Think

• 從頭跟尾往中間比對，只要有一個是不相同的就回傳`False`

### Code

#### Python

``````class Solution:
def isPalindrome(self, x: int) -> bool:
x = str(x)
left = 0
right = len(x)-1

while left < right:
if x[left] != x[right]:
return False

left += 1
right -= 1

return True
``````

### Result

• Python

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