PROGRAM TO IMPLEMENT STACK USING ARRAYS
# Python program for implementation of stack
# import maxsize from sys module
# Used to return -infinite when stack is empty
from sys import maxsize
# Function to create a stack. It initializes size of stack as 0
def createStack():
stack = []
return stack
# Stack is empty when stack size is 0
def isEmpty(stack):
return len(stack) == 0
# Function to add an item to stack. It increases size by 1
def push(stack, item):
stack.append(item)
print(item + " pushed to stack ")
# Function to remove an item from stack. It decreases size by 1
def pop(stack):
if (isEmpty(stack)):
return str(-maxsize -1) # return minus infinite
return stack.pop()
# Function to return the top from stack without removing it
def peek(stack):
if (isEmpty(stack)):
return str(-maxsize -1) # return minus infinite
return stack[len(stack) - 1]
# Driver program to test above functions
stack = createStack()
push(stack, str(10))
push(stack, str(20))
push(stack, str(30))
print(pop(stack) + " popped from stack")
OUTPUT:
10 pushed into stack
20 pushed into stack
30 pushed into stack
30 popped from stack
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