[LeetCode]Palindrome Number

 1 class Solution {
 2 public:
 3     bool isPalindrome(int x) {
 4         // 负数返回false
 5         if (x < 0) {
 6             return false;
 7         }
 8         
 9         int first = 0;
10         int last = 0;
11         
12         // 计算x有多少位
13         int len = 1;
14         while (x / len >= 10) len *= 10;
15         
16         int div = 1;
17         while (true) {
18             if (len == 1) break;
19             first = (x / len) % 10;
20             last = (x / div) % 10;;
21             if (first != last) {
22                 return false;
23             }
24             
25             len /= 10;
26             div *= 10;
27         }
28         
29         return true;
30     }
31 };