Colocación de Sudo[1.3] | Diseño de pila

Dada la cantidad de consultas, debe realizar operaciones en la pila. Las consultas son de tres tipos 1, 2 y 3. Si la operación es empujar (1) entonces empujar los elementos, si las operaciones son sacar (2) entonces sacar el elemento y si es Top (3), luego imprimir el elemento en la parte superior de la pila (si la pila está vacía, escriba «-1», sin comillas).
Ejemplos: 

Input: Queries =  6
                  3
                  1 5
                  1 6
                  1 7
                  2
                  3
Output: -1
         6 
The first query is to print top, but since the stack is empty, so we print -1.
Next three queries are to push 5, 6, and 7, so we pushed them on a stack. 
Next query is pop, so we popped 7 from a stack. Final query is to print the
top, so 6 is there at the top and thus printed.

Enfoque: la pila se puede utilizar para realizar la operación dada. Si la entrada para una consulta es 1, tome otra entrada e inserte el elemento en la pila usando la función push() . Si la entrada para una consulta es 2, extraiga el elemento utilizando la función pop() en una pila. Si la entrada para una consulta es 3, imprima el elemento superior usando la función top() . 
A continuación se muestra la implementación del enfoque anterior: 
 

// C++ program for
// Sudo-Placement | Stack Design
#include <bits/stdc++.h>
using namespace std;
 
stack<int> s;
 
// function to perform type-1 operation
void _push(int n)
{
    s.push(n);
}
 
// function to perform type-2 operation
void _pop()
{
    s.pop();
}
 
// function to perform type-3 operation
void print()
{
    // if the stack is not empty
    if (!s.empty())
        cout << s.top() << endl;
    else
        cout << -1 << endl;
}
 
// Driver Code
int main()
{
    // 1st query
    print();
    // 2nd query
    _push(5);
 
    // 3rd query
    _push(6);
 
    // 4th query
    _push(7);
 
    // 5th query
    _pop();
 
    // 6th query
    print();
 
    return 0;
}

import java.util.*;
// Java program for
// Sudo-Placement | Stack Design
 
class GFG
{
 
    static Stack<Integer> s = new Stack<>();
 
    // function to perform type-1 operation
    static void _push(int n)
    {
        s.push(n);
    }
 
    // function to perform type-2 operation
    static void _pop()
    {
        s.pop();
    }
 
    // function to perform type-3 operation
    static void print()
    {
         
        // if the stack is not empty
        if (!s.empty())
        {
            System.out.println(s.peek());
        }
        else
        {
            System.out.println(-1);
        }
    }
 
    // Driver Code
    public static void main(String[] args)
    {
        // 1st query
        print();
        // 2nd query
        _push(5);
 
        // 3rd query
        _push(6);
 
        // 4th query
        _push(7);
 
        // 5th query
        _pop();
 
        // 6th query
        print();
    }
}
 
// This code contributed by Rajput-Ji

# Python3 program for
# Sudo-Placement | Stack Design
s = [];
 
# function to perform
# type-1 operation
def _push(n):
    s.append(n);
 
# function to perform
# type-2 operation
def _pop():
    s.pop();
 
# function to perform
# type-3 operation
def _print():
 
    # if the stack is not
    # empty
    if (len(s) > 0):
        print(s[len(s) - 1]);
    else:
        print("-1");
 
# Driver Code
if __name__ == '__main__':
   
    # 1st query
    _print();
     
    # 2nd query
    _push(5);
 
    # 3rd query
    _push(6);
 
    # 4th query
    _push(7);
 
    # 5th query
    _pop();
 
    # 6th query
    _print();
 
# This code is contributed by 29AjayKumar

// C# program for
// Sudo-Placement | Stack Design
using System;
using System.Collections.Generic;
 
class GFG
{
 
    static Stack<int> s = new Stack<int>();
 
    // function to perform type-1 operation
    static void _push(int n)
    {
        s.Push(n);
    }
 
    // function to perform type-2 operation
    static void _pop()
    {
        s.Pop();
    }
 
    // function to perform type-3 operation
    static void print()
    {
         
        // if the stack is not empty
        if (s.Count != 0)
        {
            Console.WriteLine(s.Peek());
        }
        else
        {
            Console.WriteLine(-1);
        }
    }
 
    // Driver Code
    public static void Main()
    {
        // 1st query
        print();
        // 2nd query
        _push(5);
 
        // 3rd query
        _push(6);
 
        // 4th query
        _push(7);
 
        // 5th query
        _pop();
 
        // 6th query
        print();
    }
}
 
/* This code contributed by PrinciRaj1992 */

<script>
// Javascript program for
// Sudo-Placement | Stack Design
 
let s=[];
 
 // function to perform type-1 operation
function _push(n)
{
    s.push(n);
}
 
// function to perform type-2 operation
function _pop()
{
    s.pop();
}
 
// function to perform type-3 operation
function  print()
{
    // if the stack is not empty
        if (s.length!=0)
        {
            document.write(s[s.length-1]+"<br>");
        }
        else
        {
            document.write(-1+"<br>");
        }
}
 
// Driver Code
 
// 1st query
print();
// 2nd query
_push(5);
 
// 3rd query
_push(6);
 
// 4th query
_push(7);
 
// 5th query
_pop();
 
// 6th query
print();
 
// This code is contributed by rag2127
</script>

-1
6