413. Reverse Integer【easy】

Reverse digits of an integer. Returns 0 when the reversed integer overflows (signed 32-bit integer).

 

Example

Given x = 123, return 321

Given x = -123, return -321

解法一：

 class Solution {
 public:
     /*
      * @param n: the integer to be reversed
      * @return: the reversed integer
      */
     int reverseInteger(int n) {
         long ret = ;

         while (n != ) {
             ret = ret *  + n % ;
             n /= ;
         }

         if (ret > INT_MAX || ret < INT_MIN) {
             return ;
         }

         return (int)ret;
     }
 };

先用long来计算防止越界，然后再把越界的处理掉。

解法二：

 class Solution {
 public:
     int reverseInteger(int x) {
         int rst = ;

         while(x != ){
             int next_rst = rst *  + x % ;
             x = x / ;
             if(next_rst /  != rst) {
                 rst  = ;
                 break;
             }
             rst = next_rst;
         }
         return rst;
     }
 };

参考@NineChapter 的代码