【剑指offer 面试题47】不用加减乘除做加法

思路：

　　利用位运算

C++：

 #include <iostream>
 using namespace std;

 int main()
 {
     int a = , b = ;
     int sum, carry;
     do
     {
         sum = a ^ b;
         carry = (a & b) << ;
         a = sum;
         b = carry;
     }
     while(b != );

     cout<<a;
 }