How to sort a stack using only Push, Pop, Top, IsEmpty, IsFull?

Question

Given a stack S, need to sort the stack using only Push, Pop, Top, IsEmpty, IsFull.

Looking for most sim

Answer 1

Sorting a stack without extra space is quite not a possibility . At least not coming to my sane mind . We can surely use the recursion stack as extra space over here . The below approach might be helful .

My approach is O(N**2) . Over here I am iterating over stack N times, every time fixing the ith element in the stack .

Firstly fixed the bottom element by popping out N elements and pushing min_element and in Second try fixed the 2nd element from bottom by popping out N-1 elements and pushing min_element except the one pushed before this And so on .

Refer to the code below for more details .

    stack stk;
    int sort_util(stack &stk,int n,int mn)
    {
        if(n==0)
        {
            stk.push(mn);
            return mn;
        }

        int vl = stk.top();
        stk.pop();

        int fmin = sort_util(stk,n-1,min(mn,vl));

        if(fmin==vl)
            return INT_MAX;
        else
            stk.push(vl);

        return fmin;
    }

    void sort_stack(stack &stk)
    {
        for(int i=stk.size();i>1;i--)
            sort_util(stk,i,stk.top());
    }