A series or sequence of numbers is usually the product of a function and can either be infinite or finite.

In this kata we will only consider finite series and you are required to return a code according to the type of sequence:

|Code|Type|Example|
|-|-|-|
|`0`|`unordered`|`[3,5,8,1,14,3]`|
|`1`|`strictly increasing`|`[3,5,8,9,14,23]`|
|`2`|`not decreasing`|`[3,5,8,8,14,14]`|
|`3`|`strictly decreasing`|`[14,9,8,5,3,1]`|
|`4`|`not increasing`|`[14,14,8,8,5,3]`|
|`5`|`constant`|`[8,8,8,8,8,8]`|

You can expect all the inputs to be non-empty and completely numerical arrays/lists - no need to validate the data; do not go for sloppy code, as rather large inputs might be tested.

Try to achieve a good solution that runs in linear time; also, do it functionally, meaning you need to build a *pure* function or, in even poorer words, do NOT modify the initial input!

Difficulty: EASY

Starter code:
def sequence_classifier(arr):
	

Solutions:
def sequence_classifier(arr):
	if all((arr[i] == arr[i + 1] for i in range(len(arr) - 1))):
		return 5
	if all((arr[i] < arr[i + 1] for i in range(len(arr) - 1))):
		return 1
	if all((arr[i] <= arr[i + 1] for i in range(len(arr) - 1))):
		return 2
	if all((arr[i] > arr[i + 1] for i in range(len(arr) - 1))):
		return 3
	if all((arr[i] >= arr[i + 1] for i in range(len(arr) - 1))):
		return 4
	return 0


TYPE_SEQ = {(1,): 1, (0, 1): 2, (-1,): 3, (-1, 0): 4, (0,): 5}

def sequence_classifier(arr):
	countSet = {(a < b) - (a > b) for (a, b) in zip(arr, arr[1:])}
	return TYPE_SEQ.get(tuple(sorted(countSet)), 0)


def sequence_classifier(arr):
	(strict, increasing, decreasing) = (True, False, False)
	for i in range(1, len(arr)):
		if arr[i] == arr[i - 1]:
			strict = False
		if arr[i] < arr[i - 1]:
			decreasing = True
		if arr[i] > arr[i - 1]:
			increasing = True
	return [increasing and decreasing, strict and increasing, not strict and increasing, strict and decreasing, not strict and decreasing, not increasing and (not decreasing)].index(True)


def sequence_classifier(arr):
	unordered = True
	strictly_increasing = True
	not_decreasing = True
	strictly_decreasing = True
	not_increasing = True
	constant = True
	for i in range(1, len(arr)):
		if arr[i - 1] != arr[i]:
			constant = False
		if arr[i - 1] <= arr[i]:
			strictly_decreasing = False
		if arr[i - 1] >= arr[i]:
			strictly_increasing = False
		if not arr[i - 1] <= arr[i]:
			not_decreasing = False
		if not arr[i - 1] >= arr[i]:
			not_increasing = False
	if constant:
		return 5
	if strictly_decreasing:
		return 3
	if strictly_increasing:
		return 1
	if not_increasing:
		return 4
	if not_decreasing:
		return 2
	return 0


def sequence_classifier(arr):
	(f, l) = (0, len(arr) - 1)
	for i in range(0, l):
		f |= 1 if arr[i] < arr[i + 1] else 2 if arr[i] == arr[i + 1] else 4
	return [0, 1, 5, 2, 3, 0, 4, 0][f]


from enum import IntEnum

class Classification(IntEnum):
	UNORDERED = 0
	INCREASING = 1
	NOT_DECREASING = 2
	DECREASING = 3
	NOT_INCREASING = 4
	CONSTANT = 5

def sequence_classifier(arr):
	unordered = True
	increasing = True
	not_decreasing = True
	decreasing = True
	not_increasing = True
	constant = True
	previous_val = None
	for val in arr:
		if previous_val is None:
			previous_val = val
			continue
		if increasing and val <= previous_val:
			increasing = False
		if not_decreasing and val < previous_val:
			not_decreasing = False
		if decreasing and val >= previous_val:
			decreasing = False
		if not_increasing and val > previous_val:
			not_increasing = False
		if constant and val != previous_val:
			constant = False
		if not unordered and (not increasing) and (not not_decreasing) and (not decreasing) and (not not_increasing) and (not constant):
			return Classification.UNORDERED
		previous_val = val
	if constant:
		return Classification.CONSTANT
	elif increasing:
		return Classification.INCREASING
	elif not_decreasing:
		return Classification.NOT_DECREASING
	elif decreasing:
		return Classification.DECREASING
	elif not_increasing:
		return Classification.NOT_INCREASING
	else:
		return Classification.UNORDERED


def sequence_classifier(arr):
	(a, l, l_) = (sorted(arr), len(arr), len(set(arr)))
	return [[0, [[3, 4][arr == a[::-1] and l_ != l], [1, 2][arr == a and l_ != l]][arr == a]][arr in [a, a[::-1]]], 5][l_ == 1]


from operator import *

def sequence_classifier(arr):
	for (op, code) in {eq: 5, gt: 1, lt: 3, ge: 2, le: 4}.items():
		if all((op(d, 0) for d in map(sub, arr[1:], arr))):
			return code
	return 0


from collections import Counter

def sequence_classifier(arr):
	types = Counter([5, 1, 2, 3, 4, 0])
	for (a, b) in zip(arr, arr[1:]):
		if a == b:
			del types[1], types[3]
		if a != b:
			del types[5]
		if a < b:
			del types[3], types[4]
		if a > b:
			del types[1], types[2]
	return next(iter(types))


def sequence_classifier(arr):
	if len(set(arr)) == 1:
		return 5
	elif sorted(arr) == arr and len(arr) == len(set(arr)):
		return 1
	elif sorted(arr) == arr:
		return 2
	elif sorted(arr[::-1]) == arr[::-1] and len(arr) == len(set(arr)):
		return 3
	elif sorted(arr[::-1]) == arr[::-1]:
		return 4
	else:
		return 0