Submission #8000705

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Source Code Expand

N = int(input())
A = [int(i) for i in input().split()]
mod = 10**9+7
#並びが可能なら、2**(N//2)
#無理なら0
opt = {}
for i in range(N):
  a = abs((N-i-1)-i)
  if a not in opt :
    opt[a] = 1
  else :
    opt[a] += 1 
for i in range(N):
  if A[i] not in opt or opt[A[i]] == 0 :
    print(0)
    exit()
  else:
    opt[A[i]] -= 1 
ans = (2**(N//2))%mod
print(ans)

Submission Info

Judge Result