[LeetCode]7、Reverse Integer

题目描述：

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 hold integers within the 32-bit signed integer range. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

思路：

　　给出一个整数，翻转它。如123 -> 321 -123 ->-321 320 ->23
　　判断越界问题，int型的数值范围是 -2147483648～2147483647

public class Solution7 {
    public int reverse(int x){
        int result = 0;
        while(x!=0){
            if (Math.abs(result) > Integer.MAX_VALUE / 10) return 0;//越界判断
            result = result * 10 + x % 10;
            x = x/10;
        }
        
        return result;
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int x = 1000000009;
        Solution7 solution7 = new Solution7();
        System.out.println(solution7.reverse(x));
    }

}