[jobdu]不用加减乘除做加法

使用异或和与，模拟机器的加法。http://blog.csdn.net/htyurencaotang/article/details/11125415

#include <iostream>
#include <memory.h>
using namespace std;
 
void add(int &sum, int &carry)
{
    int a = sum ^ carry;
    int b = (sum & carry) << 1;
    sum = a;
    carry = b;
}
 
int main()
{
    int x, y;
    while (cin >> x >> y)
    {
        while (y != 0) add(x, y);
        cout << x << endl;
    }
    return 0;
}