Problem:
Score : 500 points

Problem Statement

Given are N integers A_1,\ldots,A_N.

We will choose exactly K of these elements. Find the maximum possible product of the chosen elements.

Then, print the maximum product modulo (10^9+7), using an integer between 0 and 10^9+6 (inclusive).

Constraints

1 \leq K \leq N \leq 2\times 10^5

|A_i| \leq 10^9

Input

Input is given from Standard Input in the following format:

N K
A_1 \ldots A_N

Output

Print the maximum product modulo (10^9+7), using an integer between 0 and 10^9+6 (inclusive).

Sample Input 1

4 2
1 2 -3 -4

Sample Output 1

12

The possible products of the two chosen elements are 2, -3, -4, -6, -8, and 12, so the maximum product is 12.

Sample Input 2

4 3
-1 -2 -3 -4

Sample Output 2

1000000001

The possible products of the three chosen elements are -24, -12, -8, and -6, so the maximum product is -6.

We print this value modulo (10^9+7), that is, 1000000001.

Sample Input 3

2 1
-1 1000000000

Sample Output 3

1000000000

The possible products of the one chosen element are -1 and 1000000000, so the maximum product is 1000000000.

Sample Input 4

10 10
1000000000 100000000 10000000 1000000 100000 10000 1000 100 10 1

Sample Output 4

999983200

Be sure to print the product modulo (10^9+7).

Solution in PyPy3 (7.3.0) (judge verdict: Wrong Answer)

import sys
from collections import deque

read = sys.stdin.read
readline = sys.stdin.readline
readlines = sys.stdin.readlines
sys.setrecursionlimit(10 ** 9)
INF = 1 << 60
MOD = 1000000007


def main():
    N, K, *A = map(int, read().split())

    A_neg = [a for a in A if a < 0]
    A_zero = [a for a in A if a == 0]
    A_pos = [a for a in A if a > 0]

    A_neg.sort(reverse=True)
    A_pos.sort()

    if N == K:
        ans = 1
        for a in A:
            ans = (ans * a) % MOD
        print(ans)
        return

    if K > len(A_neg) + len(A_pos):
        print(0)
        return
    elif len(A_pos) == 0:
        if len(A_zero) > 0:
            print(0)
            return
        elif K % 2:
            ans = 1
            for a in A_neg[:K]:
                ans = (ans * a) % MOD
            print(ans)
            return
        else:
            ans = 1
            for a in A_neg[-K:]:
                ans = (ans * a) % MOD
            print(ans)
            return

    tmp_pos = []
    tmp_neg = []

    ans = 1
    neg = 0
    for i in range(K):
        if not A_neg:
            tmp_pos.append(A_pos[-1])
            ans = ans * A_pos.pop() % MOD
        elif not A_pos:
            tmp_neg.append(A_neg[-1])
            ans = ans * A_neg.pop() % MOD
            neg = 1 - neg
        elif -A_neg[-1] > A_pos[-1]:
            tmp_neg.append(A_neg[-1])
            ans = ans * A_neg.pop() % MOD
            neg = 1 - neg
        else:
            tmp_pos.append(A_pos[-1])
            ans = ans * A_pos.pop() % MOD

    if neg:
        tmp1 = tmp2 = 0
        if A_pos and tmp_neg[-1]:
            tmp1 = A_pos[-1] / (-tmp_neg[-1])
            ans1 = ans * pow(tmp_neg[-1], MOD - 2, MOD) * A_pos.pop() % MOD
        if A_neg and tmp_pos:
            tmp2= A_neg[-1] / (-tmp_pos[-1])
            ans2 = ans * pow(tmp_pos[-1], MOD - 2, MOD) * A_neg.pop() % MOD
        
        if tmp1 > tmp2:
            ans = ans1
        else:
            ans = ans2

    print(ans % MOD)

    return


if __name__ == '__main__':
    main()