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# Collections.deque() Hacker Rank Solution – Queslers

## Problem: Collections.deque() Hacker Rank Solution

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()
>>> 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'])
``````

Perform appendpoppopleft and appendleft methods on an empty deque d.

#### Input Format :

The first line contains an integer N, the number of operations.
The next N lines contains the space separated names of methods and their values.

• 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``

### Collections.deque() Hacker Rank Solution in python 2

``````# Enter your code here. Read input from STDIN. Print output to STDOUT
from collections import deque
d=deque()
N=int(raw_input())
for i in range(N):
A=list(raw_input().split())
if A=='append':
d.append(int(A))
elif A=='appendleft':
d.appendleft(int(A))
elif A=='pop':
d.pop()
elif A=='popleft':
d.popleft()
for i in d:
print i,``````

### Collections.deque() Hacker Rank Solution in python 3

``````# Enter your code here. Read input from STDIN. Print output to STDOUT
from collections import deque
d = deque()
for _ in range(int(input())):
inp = input().split()
getattr(d, inp)(*[inp] if len(inp) > 1 else [])
print(*[item for item in d])``````

### Collections.deque() Hacker Rank Solution in pypy

``````# Enter your code here. Read input from STDIN. Print output to STDOUT
from collections import deque
d = deque()
for i in range(input()):
eval('d.{0}({1})'.format(*raw_input().split()+['']))
print ' '.join(map(str,d)) ``````

### Collections.deque() Hacker Rank Solution in pypy 3

``````# https://www.hackerrank.com/challenges/py-collections-deque?h_r=next-challenge&h_v=zen

from collections import deque

d = deque()
for i in range(int(input())):

operation, *number = input().split()
if number:
num1 = int(number)
if operation == 'append':
d.append(num1)
elif operation == 'appendleft':
d.appendleft(num1)
elif operation == 'pop':
d.pop()
elif operation == 'popleft':
d.popleft()

for i in range(len(d)):
print(d.popleft(), end = ' ')``````
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