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 Python (3.8.2) (judge verdict: Wrong Answer)

import bisect
N ,K = map(int, input().split())
A = list(map(int, input().split()))
A = sorted(A)
mod = 10 ** 9 + 7
  
# ans = minus
plus = bisect.bisect_right(A, 0)
minus = bisect.bisect_left(A, 0) 
if N == K:
  ans = 1
  for i in range(N):
    ans *= A[i]
    ans %= mod
  print(ans % mod)
  quit()
  
if (minus == N) and (K % 2 == 1):
  ans = 1
  for i in range(1, K + 1):
    ans *= A[-i]
    ans %= mod
  print(ans % mod)
  quit()
  
ans = 1

count = 0
i = 0
j = -1
while count < K:
  if K - count >= 2:
    fo = A[i] * A[i + 1]
    re = A[j] * A[j - 1]
    #print(fo, re)
    if fo >= re:
      ans *= (fo % mod) 
      ans %= mod
      i += 2
    elif (A[j - 1] <= 0) or (A[j - 2] <= 0):
      if (K % 2 == 0):
        ans *= (re % mod)
        ans %= mod
        j -= 2
      else:  
        ans *= (fo % mod) 
        ans %= mod
        i += 2      
    else:
      ans *= (re % mod)
      ans %= mod
      j -= 2
    count += 2  
  else:
    count += 1
    ans *= A[j]
      
  #print(ans)
print(ans % mod)