【朱迪的LeetCode刷题笔记】9. Palindrome Number #Easy #C
9. Palindrome Number #Easy
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 1:
Input: x = 121
Output: true
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.
Example 3:
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:
-231 <= x <= 231 - 1
Follow up: Could you solve it without converting the integer to a string?
C
#include <limits.h>
bool isPalindrome(int x){
if (x < 0) {
return false;
}
if (x == 0) {
return true;
}
int temp_x = x;
int reverse_x = 0;
while (temp_x) {
if (reverse_x > (INT_MAX - (temp_x % 10)) / 10) {
return x / 10 == reverse_x && x % 10 == temp_x;
}
reverse_x = (reverse_x * 10) + (temp_x % 10);
temp_x = temp_x / 10;
}
return reverse_x == x;
}
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