description: Vupsen and Pupsen were gifted an integer array. Since Vupsen doesn't like the number 0, he threw away all numbers equal to 0 from the array. As a result, he got an array a of length n.
  
  Pupsen, on the contrary, likes the number 0 and he got upset when he saw the array without zeroes. To cheer Pupsen up, Vupsen decided to come up with another array b of length n such that ∑_{i=1}^{n}a_i ⋅ b_i=0. Since Vupsen doesn't like number 0, the array b must not contain numbers equal to 0. Also, the numbers in that array must not be huge, so the sum of their absolute values cannot exceed 10^9. Please help Vupsen to find any such array b!
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 100) — the number of test cases. The next 2 ⋅ t lines contain the description of test cases. The description of each test case consists of two lines.
  
  The first line of each test case contains a single integer n (2 ≤ n ≤ 10^5) — the length of the array.
  
  The second line contains n integers a_1, a_2, …, a_n (-10^4 ≤ a_i ≤ 10^4, a_i ≠ 0) — the elements of the array a.
  
  It is guaranteed that the sum of n over all test cases does not exceed 2 ⋅ 10^5.
  
  Output
  
  For each test case print n integers b_1, b_2, …, b_n — elements of the array b (|b_1|+|b_2|+… +|b_n| ≤ 10^9, b_i ≠ 0, ∑_{i=1}^{n}a_i ⋅ b_i=0).
  
  It can be shown that the answer always exists.
  
  Example
  
  Input
  
  
  3
  2
  5 5
  5
  5 -2 10 -9 4
  7
  1 2 3 4 5 6 7
  
  
  Output
  
  
  1 -1
  -1 5 1 -1 -1
  -10 2 2 -3 5 -1 -1
  
  Note
  
  In the first test case, 5 ⋅ 1 + 5 ⋅ (-1)=5-5=0. You could also print 3 -3, for example, since 5 ⋅ 3 + 5 ⋅ (-3)=15-15=0
  
  In the second test case, 5 ⋅ (-1) + (-2) ⋅ 5 + 10 ⋅ 1 + (-9) ⋅ (-1) + 4 ⋅ (-1)=-5-10+10+9-4=0.
solution: import sys
  input = lambda: sys.stdin.readline().rstrip('\r\n')
  
  import math
  
  inp_vars_int = lambda: map(int, input().split())
  inp_list_int = lambda: list(map(int, input().split()))
  
  t = int(input())
  
  for _ in range(t):
      _ = int(input())
      a = inp_list_int()
      n = len(a)
      a_s = sorted(enumerate(a), key = lambda x: x[1])
      min_diff = math.inf
      i_d = None
      for i in range(1, n):
          diff = a_s[i][1] - a_s[i-1][1]
          if  0 < diff < min_diff:
              i_d = i
              min_diff = diff
      cs = 0
      
      if min_diff in (math.inf, 0):
          b = [1] * (n-1) + [1 - n]
      else:
          b = [None for _ in range(len(a))]
          d2, d1 = a_s[i_d][0], a_s[i_d - 1][0]
          for i, ai in enumerate(a):
              if i in(d1, d2):
                  continue
              sig = (cs > 0) == (ai > 0)
              bi = (1 - 2 * sig) * min_diff
              b[i] = bi
              cs += bi * ai
          mult = cs // min_diff
          if mult != 0:
              b[d2], b[d1] = -mult, mult
          else:
              a2, a1 = a[d2], a[d1]
              b[d2], b[d1] = a1 * math.gcd(a2 , a1), -a2 * math.gcd(a2 , a1)
      print(*b)
      # print(sum(ai * bi for ai, bi in zip(a, b)))