How do you sort a stack using recursion in C++?By using another stackBy using a queueBy using a linked listBy using a temporary variable

Sorting a stack using recursion in C++ can be done by using another stack. Here are the steps:

1. Create a helper stack.
2. Pop the top element from the original stack.
3. If the helper stack is empty or the top element of the helper stack is less than the popped element, push the popped element to the helper stack.
4. If the top element of the helper stack is greater than the popped element, pop all elements from the helper stack and push them to the original stack until you find an element less than the popped element or the helper stack is empty, then push the popped element to the helper stack.
5. Repeat steps 2-4 until the original stack is empty.
6. Finally, the helper stack will have all the elements sorted.

Here is the C++ code for the above steps:

void sortedInsert(stack<int> &s, int x)
{
    if (s.empty() || x > s.top())
    {
        s.push(x);
        return;
    }
    int temp = s.top();
    s.pop();
    sortedInsert(s, x);
    s.push(temp);
}

void sortStack(stack<int> &s)
{
    if (!s.empty())
    {
        int x = s.top();
        s.pop();
        sortStack(s);
        sortedInsert(s, x);
    }
}

In the above code, sortStack function is used to pop all elements from the original stack and sortedInsert function is used to insert the elements in sorted order into the helper stack.