[Programming questions] do not do addition and subtraction, multiplication and division. A write function, and the sum of two integers, the function may not be used in vivo requires +, -, *, / four arithmetic symbols.

A write function, and the sum of two integers, the function may not be used in vivo requires +, -, *, / four arithmetic symbols.

1. ++ - - Operator

class Solution 
{
public:
	int Add(int num1, int num2)
	{
		if (num1 > 0)
		{
			while (num1--)
				num2++;
		}
		else 
		{
			while (num1++)
				num2--;
		}
		return num2;
	}
};

2. Use bit arithmetic

class Solution 
{
public:
	int Add(int num1, int num2)
	{
		while (num2 != 0) 
		{
			int temp = num1 ^ num2;
			num2 = (num1 & num2) << 1;
			num1 = temp;
		}
		return num1;
	}
};

class Solution 
{
public:
	int Add(int num1, int num2)
	{
		return num2 ? Add(num1 ^ num2, (num1 & num2) << 1) : num1;
	}
};

class Solution 
{
public:
	int Add(int num1, int num2)
	{
		if (num2 == 0)
			return num1;
		return Add(num1 ^ num2, (num1 & num2) << 1);
	}
};