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/* * Reverse digits of an integer. * Example1: x = 123, return 321 * Example2: x = -123, return -321 * If the integer's last digit is 0, what should the output be? ie, cases such * as 10, 100. * Did you notice that the reversed integer might overflow? Assume the input  * is a 32-bit integer, then the reverse of 1000000003 overflows. How should  * you handle such cases? * Throw an exception? Good, but what if throwing an exception is not an  * option? You would then have to re-design the function (ie, add an extra  * parameter).  */
 * Reverse digits of an integer.

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

 * If the integer's last digit is 0, what should the output be? ie, cases such
 * as 10, 100.

 * Did you notice that the reversed integer might overflow? Assume the input 
 * is a 32-bit integer, then the reverse of 1000000003 overflows. How should 
 * you handle such cases?

 * Throw an exception? Good, but what if throwing an exception is not an 
 * option? You would then have to re-design the function (ie, add an extra 
 * parameter). 
 */

//注意：前导0和溢出的情况
//x % 10 的结果会带上x的符号
//溢出则返回负数
public class ReverseInteger {
    
    public int reverse(int x) {
        int result = 0;
        while (x != 0) {
            result = 10 * result + x % 10;
            x /= 10;
        }
        return result;
    }    
}