[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
1 public class Solution7 { 2 public int reverse(int x){ 3 int result = 0; 4 while(x!=0){ 5 if (Math.abs(result) > Integer.MAX_VALUE / 10) return 0;//越界判断 6 result = result * 10 + x % 10; 7 x = x/10; 8 } 9 10 return result; 11 } 12 public static void main(String[] args) { 13 // TODO Auto-generated method stub 14 int x = 1000000009; 15 Solution7 solution7 = new Solution7(); 16 System.out.println(solution7.reverse(x)); 17 } 18 19 }