HackerRank Python Solution - Collections Topic - deque()

• A deque is a double-ended queue. It can be used to add or remove elements from both ends.

• Deques support thread-safe, memory-efficient appends, and pops from either side of the deque with approximately the same O(1) performance in either direction.

Example Code:

>>> from collections import deque
>>> d = deque()
>>> d.append(1)
>>> print d
deque([1])
>>> d.appendleft(2)
>>> print d
deque([2, 1])
>>> d.clear()
>>> print d
deque([])
>>> d.extend('1')
>>> print d
deque(['1'])
>>> d.extendleft('234')
>>> print d
deque(['4', '3', '2', '1'])
>>> d.count('1')
1
>>> d.pop()
'1'
>>> print d
deque(['4', '3', '2'])
>>> d.popleft()
'4'
>>> print d
deque(['3', '2'])
>>> d.extend('7896')
>>> print d
deque(['3', '2', '7', '8', '9', '6'])
>>> d.remove('2')
>>> print d
deque(['3', '7', '8', '9', '6'])
>>> d.reverse()
>>> print d
deque(['6', '9', '8', '7', '3'])
>>> d.rotate(3)
>>> print d
deque(['8', '7', '3', '6', '9'])

Task:

Perform append, pop, pop left, and append left methods on an empty deque d.

Input Format:

• The first line contains an integer N, the number of operations.

• The next N lines contain the space-separated names of methods and their values.

Constraints:

• 0 < N <= 100

Output Format:

Print the space-separated elements of deque d.

Sample Input:

6
append 1
append 2
append 3
appendleft 4
pop
popleft

Sample Output:

1 2

Solution:

from collections import deque

N = int(input())

d = deque()

for _ in range(N):
    lst = input().split()
    if len(lst) > 1:
        getattr(d,lst[0])(lst[1])
    else:
        getattr(d,lst[0])()
        
print(*[item for item in d])

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