Description
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.
Solution
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class Solution {
public:
bool isPalindrome(int x) {
if (x == 0) {
return true;
}
if (x < 0) {
return false;
}
unsigned char arr[15];
int digit = 0;
while (x) {
arr[digit] = (unsigned char)(x % 10);
x /= 10;
digit++;
}
unsigned char *p = arr;
unsigned char *q = arr + (digit - 1);
while (q - p > 0) {
if (*p != *q) {
return false;
}
p++;
q--;
}
return true;
}
};
Runtime: 8 ms, faster than 77.56% of C++ online submissions for Palindrome Number.
Memory Usage: 5.9 MB, less than 29.51% of C++ online submissions for Palindrome Number.
