如把31转换为14，须要改变2个bit位。

(31)10=(11111)2

(14)10=(01110)2

贴代码

class Solution {

public:

    /**

     *@param a, b: Two integer

     *return: An integer

     */

    int bitSwapRequired(int a, int b) {

        // write your code here

        unsigned int  flag = 1;

        int i =0;

        int j = 0;

        int c= 0;

        while (flag) {

            i = a & flag;

            j = b & flag;

           if (i ^ j) {

               c++;

           }

            flag = flag << 1;

        }

        return c;

    }

};