【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 = 11, b = 17;
    int sum, carry;
    do
    {
        sum = a ^ b;
        carry = (a & b) << 1;
        a = sum;
        b = carry;
    }
    while(b != 0);

    cout<<a;
}