Delete middle element of a stack

Problem Statement - link #

Given a stack with push(), pop(), empty() operations, delete the middle of the stack without using any additional data structure. Middle: ceil((size_of_stack+1)/2) (1-based index)

Your Task: You don’t need to read input or print anything. Complete the function deleteMid() which takes the stack and its size as input parameters and modifies the stack in-place. Note: The output shows the stack from top to bottom.

Expected Time Complexity: O(N) Expected Auxiliary Space: O(N)

Examples #

Example 1:

Input: 
Stack = {1, 2, 3, 4, 5}
Output:
ModifiedStack = {1, 2, 4, 5}
Explanation:
As the number of elements is 5 , 
hence the middle element will be the 3rd
element which is deleted

Example 2:

Input: 
Stack = {1 2 3 4}
Output:
ModifiedStack = {1 3 4}
Explanation:
As the number of elements is 4 , 
hence the middle element will be the 2nd
element which is deleted

Constraints #

• 2 ≤ size of stack ≤ 100

Solutions #

class Solution
{
    public:
    //Function to delete middle element of a stack.
    void del(stack<int>&s, int n, int c){
        if(c==n/2) { s.pop(); return; }
        int d = s.top();
        s.pop();
        del(s,n,c+1);
        s.push(d);
    }
    void deleteMid(stack<int>&s, int sizeOfStack)
    {
        // code here.. 
        del(s,sizeOfStack,0);
    }
};