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.

 

反转一个int类型数。

方法1：x%10,x/=10

方法2：反转字符

肯定是方法1快点，但是我就是想写慢的....

 1 public class Solution {
 2     public int Reverse(int x) {
 3         if (x == 0)
 4             return 0;
 5         if (x == -2147483648)
 6             return 0;
 7         bool isNega = false;
 8         if (x < 0)
 9             isNega = true;
10         x = isNega ? -x : x;
11         string tmpStr = x.ToString();
12         int length = tmpStr.Length;
13         string resultStr = string.Empty;
14         for (int i = 0; i < length / 2; i++)
15             resultStr += tmpStr[length - 1 - i];
16         if (length % 2 == 1)
17             resultStr += tmpStr[length / 2];
18         for (int i = 0; i < length / 2; i++)
19             resultStr += tmpStr[length / 2 - 1 - i];
20         long result = Convert.ToInt64(resultStr);
21         if (isNega)
22             result = -result;
23         if (result < int.MinValue || result > int.MaxValue)
24             return 0;
25         return (int)result;
26     }
27 }