# Task
 Some people are standing in a row in a park. There are trees between them which cannot be moved. 
 
 Your task is to rearrange the people by their heights in a non-descending order without moving the trees.

# Example

 For `a = [-1, 150, 190, 170, -1, -1, 160, 180]`, the output should be

 `[-1, 150, 160, 170, -1, -1, 180, 190]`.

# Input/Output


 - `[input]` integer array `a`

    If a[i] = -1, then the ith position is occupied by a tree. Otherwise a[i] is the height of a person standing in the ith position.

    Constraints:

    `5 ≤ a.length ≤ 30,`

    `-1 ≤ a[i] ≤ 200.`


 - `[output]` an integer array

    `Sorted` array a with all the trees untouched.

Difficulty: EASY
Starter code: def sort_by_height(a):
	

Solutions:
def sort_by_height(a):
	s = iter(sorted((x for x in a if x != -1)))
	return [x if x == -1 else next(s) for x in a]


def sort_by_height(arr):
	heights = iter(sorted((i for i in arr if i > 0)))
	for (idx, i) in enumerate(arr):
		if i > 0:
			arr[idx] = next(heights)
	return arr


def sort_by_height(a):
	people = iter(sorted([i for i in a if i != -1]))
	return [i if i == -1 else next(people) for i in a]


def sort_by_height(a):
	filtered = list(sorted(filter(lambda x: x != -1, a), key=lambda x: -x))
	return [-1 if i == -1 else filtered.pop() for i in a]


def sort_by_height(arr):
	s = sorted((n for n in arr if n != -1))
	return [n if n == -1 else s.pop(0) for n in arr]


def sort_by_height(a):
	people = sorted([j for j in a if j != -1])
	for i in range(len(a)):
		if a[i] != -1:
			a[i] = people.pop(0)
	return a


def sort_by_height(a):
	it = iter(sorted([x for x in a if x >= 0]))
	return [x if x < 0 else next(it) for x in a]


def sort_by_height(a):
	list_index = [x for (x, i) in enumerate(a) if i == -1]
	list_sorted = sorted([i for (x, i) in enumerate(a) if i != -1])
	for new_item in list_index:
		list_sorted.insert(new_item, -1)
	return list_sorted


def sort_by_height(a):
	(h, k) = (sorted([i for i in a if i != -1]), [])
	for i in a:
		if i != -1:
			k += [h[0]]
			h = h[1:]
		else:
			k += [i]
	return k