Stacks In Python 4

Stack implementation:1

(WithOut Using Functions)

To maintain elements using a stack

Operations:
Addition of elements (PUSH)
Deletion of elements (POP)
Traversal of elements (DISPLAY)

Creation of empty stack

s=[]

Push operation

a=input(“Enter any element “)
s.append(a)

Pop operation

if(s==[]):
    print(“Underflow / stack is empty”)
else:
    print(“poped element is “,s.pop())

To check stack is empty or not

if(s==[]):
    print(“stack is empty”)
else:
    print(“stack is not empty”)

Travesal operation

n=len(s)
for i in range(n-1,-1,-1):
     print(s[i])

Source Code

#stack implementation
s=[]
while True:
    print("1. Push");
    print("2. Pop");
    print("3. Traversal")
    print("4. Exit")
    ch=int(input("Enter your choice "))
    if(ch==1):
        a=input("Enter any element ")
        s.append(a)
    elif(ch==2):
        if(s==[]):
            print("Underflow /  stack is empty")
        else:
            print("poped element is ",s.pop())
    elif(ch==3):
        n=len(s)
        for i in range(n-1,-1,-1):
            print(s[i])
    elif(ch==4):
        print("End")
        break
    else:
        print("Invalid choice")

Output:

1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 1
Enter any element 10
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 3
10
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 1
Enter any element 20
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 3
20
10
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 1
Enter any element hello
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 3
hello
20
10
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 2
poped element is  hello
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 3
20
10
1. Push
2. Pop
3. Traversal
4. Exit
Enter your choice 4
End
>>> 

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