LeetCode-in-All
7. Reverse Integer
Medium
Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.
Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
Example 1:
Input: x = 123
Output: 321
Example 2:
Input: x = -123
Output: -321
Example 3:
Input: x = 120
Output: 21
Example 4:
Input: x = 0
Output: 0
Constraints:
-231 <= x <= 231 - 1
Solution
class Solution {
/**
* @param Integer $x
* @return Integer
*/
public function reverse($x) {
$ls_negative = '';
if (strpos($x, '-') === 0) {
$ls_negative = substr($x, 0, 1);
$x = substr($x, 1);
}
$la_chars = str_split($x);
$la_chars = array_reverse($la_chars);
$li_result = intval($ls_negative . implode('', $la_chars));
if ($li_result > 2147483647 || $li_result < -2147483647) {
$li_result = 0;
}
return $li_result;
}
}