Stack

• An ordered list.
• Deletion and insertion all made at one end i.e., LIFO (last in first out)
• Stack has basic three operations which can be performed on stack, namely push, pop, and peek
• push: to insert an element
• pop: to remove the topmost element
• peek: to look what's at the top of the stack without removing it
• Every stack operation takes constant time. O(1)

Stacks are usually not dynamic in nature, if implemented using static arrays. But they can be made dynamic using linkedlists or dynamic lists in python.

To see the implementation of stack using linkedlist click here.

How to use a stack in python?

install the data structure library using

pip install Gsauce-pyds

Example

from dstructure.stack import Stack2

s = Stack2(range(3))
print(s,len(s))

# output:
# Stack([0,1,2]) 3

s.push(3)
s.push(5)
print(s,len(s))

# output:
# Stack([0,1,2,3,5]) 5


s.pop()
print(s,len(s))

# output:
# Stack([0,1,2,3]) 4

print(s.peek)
# 3

A few applications of stacks

• Post fix notation
• Recursion
• Fibonacci series
• permutations ...... etc.