Color The Code: pop

Friday, October 30, 2020

CREATING STACK IN PYTHON

CREATING STACK USING PYTHON

OPERATIONS:

1- PUSH

2- POP

OTHER OPERATIONS:

1- IS EMPTY

2- SIZE

3- TOP

CODE :

We can implement stack using :

1- list

2- collections.deque

3- queue.LifoQueue

1 - IMPLEMENTING STACK USING LIST

CODE:

stack = [] // list is created to be used as stack
stack.append('a') // append() push the element in stack which is actually a list
stack.append('b')
stack.append('c')

print(stack.pop()) // pop() is used to pop / delete element on top of list
print(stack.pop())
print(stack.pop())

print(stack)

2- IMPLEMENTING STACK USING collections.deque

from collections import deque // importing the library
stack = deque() // initializing a variable

stack.append('a') // append function to insert element
stack.append('b')
stack.append('c')

print(stack.pop()) // pop() function to remove the top element
print(stack.pop())
print(stack.pop())

print(stack)

3- IMPLEMENTING STACK USING queue module

Functions available in this module are :

1- get() - remove and return the element from queue

2- put(element) - put element in the queue

3- maxsize() - maximum elements allowed

4- empty() - check whether stack is empty or not

5- full() - check whether stack is full or not if maxsize is declared

6- qsize() - get number of items in queue

CODE:

from queue import LifoQueue
stack = LifoQueue(maxsize = 5) // initializing stack with maxsize = 5
print(stack.qsize()) // show the number of elements in the stack
stack.put('a') // put() is used to push elements in the stack
stack.put('b')
stack.put('c')
print("Full: ", stack.full()) // is the stack full or does stack contain maxsize elements
print(stack.get()) // return and remove the top element of the stack
print(stack.get())
print(stack.get())
print("Is Empty : ", stack.empty()) // test is the stack empty or not

CREATING STACK USING STL

STACK IN STL

Standard library provides us stack container with number of built in features.

STACK TEMPLATE :

template <class T, class Container = deque<T> > class stack;

MEMBER FUNCTIONS :

All these operations can be performed in 0(1)

empty : test whether the container is empty

size : return the size of the container

top : return the top element

push : insert element

emplace : construct and insert element

pop : remove top element

swap : swap contents

CODE ;

#include <iostream>
#include <stack> // for using stack container
using namespace std;

int main()
{
int sum = 0;
stack<int> mystack; // declaring stack
mystack.push(21); // inserting element
mystack.push(32);
mystack.push(23);
mystack.push(63);
mystack.push(212);

while (!mystack.empty()) { // checking the empty condition
sum = sum + mystack.top(); // checking the top element
mystack.pop(); // performing pop operation
}
cout << sum;
return 0;
}