Reverse Integer

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.

注意越界

时间 o(n), space o(1)

class Solution {
    public int reverse(int x) {
        long res = 0;
        
        while( x!= 0){
            res = res *10 + x %10;
            x /= 10;
            
            if(res > Integer.MAX_VALUE || res < Integer.MIN_VALUE) return 0;
        }
        
        return (int)res;
    }
}

犯错，res应该是long，同时check 是不是比int最大值 最小值大