Friday 21 August 2020

Write a Python program to implement a stack using a list data-structure.

Data Structure: Data structure can be defined either mathematically or logically is called Data structure.

Types of Data Structure:











Stack: It is a mathematical tool, it works on the principle of last in first out(LIFO or first in last out(FILO)

* Inserting element to the stack is push and Removing element from the stack is pop


PROGRAM:

 




OUTPUT:



#PROGRAM FOR STACK OPERATION

#PREPARED BY RKS

def isEmpty(stk):

    if stk==[]:

        return True

    else:

        return False


def Push(stk, item):

    stk.append(item)

    top=len(stk)-1


def Pop(stk):

    if isEmpty(stk):

        return "Underflow"

    else:

        item=stk.pop()

        if len(stk)==0:

            top=None

        else:

            top=len(stk)-1

        return item

def Peek(stk):

    if isEmpty(stk):

        return "Underflow"

    else:

        top=len(stk)-1

    return item

def Peek(stk):

    if isEmpty(stk):

        return "Underflow"

    else:

        top=len(stk)-1

        return stk[top]

def disp(stk):

    if isEmpty(stk):

        print("Stack Empty")

    else:

        top=len(stk)-1

        print(stk[top],"<-top")

        for a in range(top-1,-1,-1):

            print(stk[a])


stack=[]

top=None

while True:

    print("\n\nStack Operations:")

    print("1. Push")

    print("2. Pop")

    print("3. Peek")

    print("4. Display Stack")

    print("5. Exit")

    ch=int(input("Enter your choice : "))

    if ch==1:

        item=int(input("Enter Item:"))

        Push(stack,item)

    elif ch==2:

        item=Pop(stack)

        if item=="Underflow":

            print("stack is empty")

        else:

            print("Popped item is : ",item)

    elif ch==3:

        item=Peek(stack)

        if item=="Underflow":

            print("Stack is empty")

        else:

            print("Topmost item is : ",item)

    elif ch==4:

        disp(stack)

    elif ch==5:

        break

    else:

        print("Invalid Choice ")

        

        

    


            

            

        

        


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