leetcode 7

7. Reverse Integer

• Total Accepted: 152273
• Total Submissions: 640718
• Difficulty: Easy

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

思路：使用使用循環左移的思想，再移動期間判斷是否溢出。

public class Solution {
    public int reverse(int x) {
        int res = 0;
        
        while(x != 0){
            int tail = x%10;
            int next = res*10 + tail;
            if((next-tail)/10 != res){
                return 0;
            }
            res = next;
            x = x/10;
        }
        return res;
                
    }
}