[leetcode]LeetCode刷题的日子--Reverse Integer

简单题，迅速过

题目：

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

题目翻译：

倒置一个int数即可，注意越界

解题思路：

略

代码：

fn reverse(x: i32) -> i32 {
    let mut num = x;
    let mut reverse_num: i64 = 0;
    while num != 0 {
        reverse_num = reverse_num * 10 + (num % 10) as i64;
        num = num / 10;
    }

    if reverse_num > std::i32::MAX as i64 || reverse_num < std::i32::MIN as i64 {
        return 0;
    }

    return reverse_num as i32;
}

#[test]
fn test_reverse() {
    let demo1 = -123;
    let ret = reverse(demo1);
    assert_eq!(ret, -321);
}