Swapping without temporary storage

Give a method to swap two numbers without using additional memory.

Solution :

1. We may use addition/subtraction or XOR to achieve this.
2. XOR does not cause overflows and hence is superior.

Complexity :

• Time : O(1)
• Space : O(1)

Code :

void swap_xor(int &num1, int &num2){

num1 ^= num2;
num2 ^= num1;
num1 ^= num2;

}

void swap(int &num1, int &num2){

num1 = num1 + num2;
num2 = num1 - num2;
num1 = num1 - num2;

}