LeetCode 7. Reverse Integer

7. Reverse Integer

Difficulty: Easy

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.

Solution

Language: Java

class Solution {
    public int reverse(int x) {
        if (x == 0) {
            return 0;
        }
        long y = x;
        boolean isMinus = false;
        if (y < 0) {
            isMinus = true;
            y = -y;
        }
        long ans = 0;
        while (y != 0) {
            ans = ans * 10 + y % 10;
            y /= 10;
        }
        if ((!isMinus && ans > Integer.MAX_VALUE) || -ans < Integer.MIN_VALUE) {
            return 0;
        } else {
            return (int) (isMinus ? -ans : ans);
        }
    }
}