CPP

reverse a stack in c++ using another stack

// C++ program to reverse a stack
// by using an extra stack
#include <bits/stdc++.h>
using namespace std;
 
// Function to transfer elements of
// the stack s1 to the stack s2
void transfer(stack<int>& s1,
              stack<int>& s2, int n)
{
    for (int i = 0; i < n; i++) {
 
        // Store the top element
        // in a temporary variable
        int temp = s1.top();
 
        // Pop out of the stack
        s1.pop();
 
        // Push it into s2
        s2.push(temp);
    }
}
 
// Function to reverse a stack using another stack
void reverse_stack_by_using_extra_stack(stack<int>& s,
                                        int n)
{
    stack<int> s2;
 
    for (int i = 0; i < n; i++) {
 
        // Store the top element
        // of the given stack
        int x = s.top();
 
        // Pop that element
        // out of the stack
        s.pop();
 
        transfer(s, s2, n - i - 1);
        s.push(x);
        transfer(s2, s, n - i - 1);
    }
}
 
// Driver Code
int main()
{
    int n = 5;
 
    stack<int> s;
    s.push(1);
    s.push(2);
    s.push(3);
    s.push(4);
    s.push(5);
 
    reverse_stack_by_using_extra_stack(s, n);
 
    for (int i = 0; i < n; i++) {
        cout << s.top() << " ";
        s.pop();
    }
    return 0;
}