Average Height (Codeforces 1509A)
Tags: Others, constructive algorithms

Sayaka Saeki is a member of the student council, which has $$$n$$$ other members (excluding Sayaka). The $$$i$$$-th member has a height of $$$a_i$$$ millimeters.It's the end of the school year and Sayaka wants to take a picture of all other members of the student council. Being the hard-working and perfectionist girl as she is, she wants to arrange all the members in a line such that the amount of photogenic consecutive pairs of members is as large as possible.A pair of two consecutive members $$$u$$$ and $$$v$$$ on a line is considered photogenic if their average height is an integer, i.e. $$$\frac{a_u + a_v}{2}$$$ is an integer.Help Sayaka arrange the other members to maximize the number of photogenic consecutive pairs.

Input: The first line contains a single integer $$$t$$$ ($$$1\le t\le 500$$$) — the number of test cases.The first line of each test case contains a single integer $$$n$$$ ($$$2 \le n \le 2000$$$)  — the number of other council members.The second line of each test case contains $$$n$$$ integers $$$a_1$$$, $$$a_2$$$, ..., $$$a_n$$$ ($$$1 \le a_i \le 2 \cdot 10^5$$$)  — the heights of each of the other members in millimeters.It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2000$$$.

Output: For each test case, output on one line $$$n$$$ integers representing the heights of the other members in the order, which gives the largest number of photogenic consecutive pairs. If there are multiple such orders, output any of them.

Note: In the first test case, there is one photogenic pair: $$$(1, 1)$$$ is photogenic, as $$$\frac{1+1}{2}=1$$$ is integer, while $$$(1, 2)$$$ isn't, as $$$\frac{1+2}{2}=1.5$$$ isn't integer.In the second test case, both pairs are photogenic.

Sample Inputs:
4
3
1 1 2
3
1 1 1
8
10 9 13 15 3 16 9 13
2
18 9

Sample Outputs:
1 1 2 
1 1 1 
13 9 13 15 3 9 16 10 
9 18

Solution (Python):
for _ in range(int(input())):
    n = int(input())
    a = sorted(map(int, input().split()), key=lambda x: x & 1)
    print(*a)

Solution (Python):
for i in range(int(input())):
    a = int(input())
    b = list(map(int, input().split()))
    c = []
    d = []
    for j in b:
        if j % 2:
            c.append(j)
        else:
            d.append(j)
    print(*c, *d)

Solution (Python):
for s in [*open(0)][2::2]:
    print(*sorted(s.split(), key=lambda x: int(x) & 1))