## [7\. Reverse Integer](https://leetcode.com/problems/reverse-integer/)

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

**Constraints:**

- `-231 <= x <= 231 - 1`

class Solution {
public:
    int reverse(int x) {
        int reversed = 0;
        while(x != 0) {
            int digit = x % 10;
            x /= 10;
            if(reversed > INT_MAX / 10 || (reversed == INT_MAX / 10 && digit > INT_MAX % 10))
                return 0;
            if(reversed < INT_MIN / 10 || (reversed == INT_MIN / 10 && digit < INT_MIN % 10))
                return 0;
            reversed = reversed * 10 + digit;
        }
        return reversed;
    }
};

:::success
- 時間複雜度：$O(\log N)$
- 空間複雜度：$O(1)$
:::