Reverse the stack

Algorithm

1. Insert function.

   • if the stack is empty, push the element.
   • Get the top element.
   • Recursively call the insert function with reduced elements.
   • push the temp element.

2. reverse function.

   • Base condition. If stack has only one element then return.
   • Get the top element.
   • Recursively call the reverse function with Reduced input.
   • insert the temp element to the stack.

Code

void inserT(stack<int> &s, int ele)
{
    if (s.empty())
    {
        s.push(ele);
        return;
    }

    int temp = s.top();
    s.pop();

    inserT(s, ele);
    s.push(temp);
}

void reverse(stack<int> &s)
{
    if (s.size() == 1)
        return;

    int temp = s.top();
    s.pop();

    reverse(s);
    inserT(s, temp);
}

References

• GFG: Reverse a stack using recursion
• YouTube: