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 java.util.*;
  import java.io.*;
  
  public class D_1582 {
  	public static void main(String[] args) throws Exception {
  		Scanner sc = new Scanner(System.in);
  		PrintWriter pw = new PrintWriter(System.out);
  		
  		int t = sc.nextInt();
  		while(t-->0) {
  			int n = sc.nextInt();
  			int[] a = sc.nextIntArray(n);
  			
  			ArrayList<Integer>[] list = new ArrayList[(int)2e4+1];
  			for(int i = 0; i < list.length; i++)
  				list[i] = new ArrayList<>();
  			
  			for(int i = 0; i < n; i++)
  				list[a[i] + (int)1e4].add(i);
  			
  			ArrayList<Integer> ones = new ArrayList<>();
  			for(int i = 0; i < list.length; i++)
  				if(list[i].size() == 1) {
  					for(int j : list[i])
  						ones.add(j);
  					list[i] = new ArrayList<>();
  				}
  			
  			if(ones.size() == 1) {
  				for(int i = 0; i < list.length; i++) {
  					if(list[i].size() == 2) {
  						for(int j : list[i])
  							ones.add(j);
  						list[i] = new ArrayList<>();
  						break;
  					} else if(list[i].size() > 2) {
  						int x = list[i].get(list[i].size() - 1);
  						ones.add(x);
  						list[i].remove(list[i].size() - 1);
  						break;
  					}
  				}
  			}
  			
  			int[] b = new int[n];
  			int index = 0;
  			if(ones.size() % 2 == 1) {
  				int x = ones.get(0), y = ones.get(1), z = ones.get(2);
  				b[x] = 2 * a[y] * a[z];
  				b[y] = -1 * a[x] * a[z];
  				b[z] = -1 * a[x] * a[y];
  				index = 3;
  			}
  			for(int i = index; i < ones.size(); i += 2) {
  				int x = ones.get(i), y = ones.get(i + 1);
  				b[x] = a[y];
  				b[y] = -1 * a[x];
  			}
  			for(int i = 0; i < list.length; i++) {
  				if(list[i].size() > 0) {
  					for(int j = 0; j < list[i].size() - 1; j++)
  						b[list[i].get(j)] = 1;
  					b[list[i].get(list[i].size() - 1)] = -1 * (list[i].size() - 1);
  				}
  			}
  			
  			for(int i = 0; i < n; i++)
  				pw.print(b[i] + (i == n - 1 ? "\n" : " "));
  		}
  		
  		pw.flush();
  	}
  
  	public static class Scanner {
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream system) {
  			br = new BufferedReader(new InputStreamReader(system));
  		}
  
  		public Scanner(String file) throws Exception {
  			br = new BufferedReader(new FileReader(file));
  		}
  
  		public String next() throws IOException {
  			while (st == null || !st.hasMoreTokens())
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public String nextLine() throws IOException {
  			return br.readLine();
  		}
  
  		public int nextInt() throws IOException {
  			return Integer.parseInt(next());
  		}
  
  		public double nextDouble() throws IOException {
  			return Double.parseDouble(next());
  		}
  
  		public char nextChar() throws IOException {
  			return next().charAt(0);
  		}
  
  		public long nextLong() throws IOException {
  			return Long.parseLong(next());
  		}
  
  		public int[] nextIntArray(int n) throws IOException {
  			int[] array = new int[n];
  			for (int i = 0; i < n; i++)
  				array[i] = nextInt();
  			return array;
  		}
  
  		public Integer[] nextIntegerArray(int n) throws IOException {
  			Integer[] array = new Integer[n];
  			for (int i = 0; i < n; i++)
  				array[i] = new Integer(nextInt());
  			return array;
  		}
  
  		public long[] nextLongArray(int n) throws IOException {
  			long[] array = new long[n];
  			for (int i = 0; i < n; i++)
  				array[i] = nextLong();
  			return array;
  		}
  
  		public double[] nextDoubleArray(int n) throws IOException {
  			double[] array = new double[n];
  			for (int i = 0; i < n; i++)
  				array[i] = nextDouble();
  			return array;
  		}
  
  		public static int[] shuffle(int[] a) {
  			int n = a.length;
  			Random rand = new Random();
  			for (int i = 0; i < n; i++) {
  				int tmpIdx = rand.nextInt(n);
  				int tmp = a[i];
  				a[i] = a[tmpIdx];
  				a[tmpIdx] = tmp;
  			}
  			return a;
  		}
  
  		public boolean ready() throws IOException {
  			return br.ready();
  		}
  
  		public void waitForInput() throws InterruptedException {
  			Thread.sleep(3000);
  		}
  	}
  }
  