Reverse Integer

Problem Description

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 [-2^31, 2^31 - 1], then return 0.

Key Insights

• The problem involves reversing the digits of an integer while handling the sign.
• Care must be taken to manage overflow conditions as specified by the constraints.
• The solution should not utilize 64-bit integers due to the limitations imposed by the environment.

Space and Time Complexity

Time Complexity: O(n), where n is the number of digits in the integer. Space Complexity: O(1), since we are using a constant amount of space for variables.

Solution

To solve the problem, we can use a mathematical approach by repeatedly extracting the last digit of the integer and constructing the reversed number. We will check for overflow conditions at each step to ensure the result stays within the 32-bit signed integer range.

1. Start with a variable to hold the reversed number initialized to 0.
2. While the integer x is not 0, do the following:
   • Extract the last digit using x % 10.
   • Remove the last digit from x using integer division by 10.
   • Before updating the reversed number, check if the current reversed number will cause an overflow when the new digit is added.
   • Update the reversed number.
3. If overflow occurs during the process, return 0.
4. Finally, return the reversed number.

Code Solutions