Reverse Integer
You are given a signed 32-bit integer x.
Return x after reversing each of its digits. After reversing, if x goes outside the signed 32-bit integer range [-2^31, 2^31 - 1], then return 0 instead.
Solve the problem without using integers that are outside the signed 32-bit integer range.
Example 1:
Input: x = 1234
Output: 4321Example 2:
Input: x = -1234
Output: -4321Example 3:
Input: x = 1234236467
Output: 0Constraints:
-2^31 <= x <= 2^31 - 1
Recommended Time & Space Complexity
You should aim for a solution with O(1) time and O(1) space.
Hint 1
A straightforward approach would be to convert the given integer to a string, reverse it, convert it back to an integer using a long type, and return 0 if the result exceeds the integer range. Can you think of a better way?
Hint 2
We initially declare the result res as an int with a value of 0. We iterate through the given integer, extracting digits one by one. Before appending a digit to res, we consider multiple cases. Can you determine them? Maybe you should think about overflow.
Hint 3
Let MAX be the maximum positive integer and MIN be the minimum negative integer. We iterate through each digit and check for overflow before updating res. If res > MAX / 10 or res < MIN / 10, return 0. If res == MAX / 10 and the current digit is greater than MAX % 10, return 0. If res == MIN / 10 and the current digit is less than MIN % 10, return 0. Otherwise, append the digit to res and continue.