Leetcode Problem 7 Reverse Integer.txt

7. Reverse Integer
Easy

2163

3287

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Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321
Example 2:

Input: -123
Output: -321
Example 3:

Input: 120
Output: 21
Note:
Assume we are dealing with an environment which could only store integers within the
32-bit signed integer range: [−231,  231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

Hint To Solve: Just take the unit digit number and keep adding to the previous result multiplied by 10.
Note: Take care of the overflow edge case. Record the previous result to check the overflow condition.

public class Solution {
    public int Reverse(int x)
    {
        int result = 0;
        int previousResult = 0;
        while(x != 0)
        {
            int unitDigit = x%10;
            previousResult = result;
            result = result * 10 + unitDigit;
            //Console.WriteLine("Result: "+ result);
            //Console.WriteLine("PrevExpected: "+ (result-unitDigit)/10);
            if(previousResult != (result-unitDigit)/10)
                return 0;
            x = x/10;
        }
        return result;
    }
}