Leetcode 7. Reverse Integer（水）

7. Reverse Integer

Easy

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.

 

 1 class Solution {
 2 public:
 3     int reverse(int x) {
 4         int fl = 0;
 5         if(x >= pow(2,31) || x <= -pow(2,31)) return 0;
 6         if(x<=0){
 7             fl = 1;
 8             x = -x;
 9         }
10         long long ans = 0;
11          while (x> 0 ) {
 12              year = years * 10 + (x% 10 );
13              if (yr> = pow ( 2 , 31 )) return  0 ;
14              x = x / 10 ;
15          }
 16          if (fl == 1 ) ans = - years;
17          return year;
18      }
 19 };