stack-queue's Introduction

Stack-Queue

Using Array and Linked LIst

#Stack Implementation//- Array class Stack: stack = [] pointer = -1

def push(self, element):
    self.stack.append(element)
    self.pointer += 1

def peek(self):
    return (self.stack[self.pointer])

def pop(self):
    value = self.stack[self.pointer]
    self.stack = self.stack[:-1]    #discarding the last item
    self.pointer -= 1
    return value

#Stack Implementation//- Array class Node: def init(self,v): self.val = v self.ref = None

class Stack: head = None

def push(self, data):
    if(self.head == None):
        self.head = Node(data) 
    else:
        n = Node(data) 
        n.ref = self.head
        self.head = n 

def peek(self):
    #check for empty list
    return self.head.val 

def pop(self):
    #check for empty list 
    temp = self.head 
    self.head = self.head.ref 
    value = temp.val  
    temp.val = None 
    temp.ref = None 
    return value

#Queue Implementation: Array

class Queue:
q = [] front = 0 rear = -1

def enqueue(self, val):
    self.q.append(val)
    self.rear += 1

def dequeue(self):
    temp = self.q[self.front]
    self.q = self.q[self.front+1:self.rear]     #excluding first value(0 index)
    self.rear -= 0 
    return temp 

def peek(self):
    return self.q[self.front]

queue = Queue() queue.enqueue(1) print("Top:", queue.peek()) queue.enqueue(2) queue.enqueue(2) print(queue.dequeue()) print(queue.peek())

#Queue implementation: Linked List

class Node: def init(self,val): self.val = val self.next = None

class Queue: head = None tail = None

def enqueue(self, data):
    n = Node(data)
    if(self.head == None):
        self.head = n
        self.tail = n
    else:
        self.tail.next = n
        self.tail = n
        
def dequeue(self):
    if(self.head == None):
        print("Empty List")
    else:
        temp = self.head 
        self.head = self.head.next 
        print("Removed:", temp.val)
        temp.val = None 
        temp.next = None 

def peek(self):
    return (self.head.val)

q = Queue() q.enqueue(1) q.enqueue(2) print(q.peek()) q.dequeue() print(q.peek())

Recommend Projects