Problem link: Stack Sort in
Problem Statement:
You are given a stack of integers. Your task is to sort the stack in ascending order using recursion. You cannot use any additional data structures besides the stack and the call stack for the recursive function calls. Implement a function that takes a stack and returns the sorted stack.
Approach:
The key idea is to use recursion to sort the stack by removing elements one by one and then inserting them back in a sorted order.

Remove Elements Recursively:
 Start by removing the top element from the stack.
 Use a recursive function to remove all elements until the stack is empty. This step will effectively reverse the order of the elements as they are removed.

Sort and Insert Back:
 Once the stack is empty, you begin to insert the elements back into the stack.
 Use a helper function to insert each element in its correct position. This function will place the element into the stack such that the elements in the stack are sorted in ascending order.

Insert Sorted Elements:
 When inserting an element, compare it with the top of the stack.
 If the current element is greater than or equal to the top element of the stack, push it onto the stack.
 If the current element is smaller, remove the top element of the stack and recursively call the insertion function to find the correct position for the current element. Then, push the removed element back onto the stack.

Maintain Order:
 By recursively removing and then inserting elements in a sorted manner, you ensure that the stack ends up being sorted in ascending order.
Time Complexity:
O(n^{2}), where n is the number of elements in the stack. Each element may be inserted back into the stack multiple times, leading to a quadratic time complexity.
Space Complexity:
O(n), due to the recursion call stack. The maximum depth of the recursion will be equal to the number of elements in the stack.