source_code: import java.io.*;
  import java.util.*;
   public class Main {
  	public static void main(String[] args) throws Exception {
  		FastIO io = new FastIO();
  		int test=io.nextInt();
  		while(test>0)
  		{
  		    int n=io.nextInt();
  		    int arr[]=new int[n];
  		    for(int i=0;i<n;i++)arr[i]=io.nextInt();
  		    List<int[]> list=new ArrayList<>();
  		    Stack<int[]> stk=new Stack<>();
  		    int temp[]={1};
  		    list.add(temp);
  		    stk.push(temp);
  		    for(int i=1;i<n;i++)
  		    {
  		        if(arr[i]==1)
  		        {
  		            int t[]=stk.peek();
  		            int nt[]=new int[t.length+1];
  		            for(int j=0;j<t.length;j++)nt[j]=t[j];
  		            nt[nt.length-1]=arr[i];
  		            stk.push(nt);
  		            list.add(nt);
  		            continue;
  		        }
  		        while(stk.size()>0)
  		        {
  		            int t[]=stk.peek();
  		            if(t[t.length-1]+1==arr[i]){
  		                int nt[]=new int[t.length];
  		                for(int j=0;j<t.length-1;j++)nt[j]=t[j];
  		                nt[t.length-1]=arr[i];
  		                stk.pop();
  		                stk.push(nt);
  		                list.add(nt);
  		                break;
  		            }
  		            else
  		            {
  		                stk.pop();
  		            }
  		        }
  		    }
  		    for(int i=0;i<list.size();i++)
  		    {
  		        StringBuilder sb=new StringBuilder();
  		        sb.append(list.get(i)[0]);
  		        for(int j=1;j<list.get(i).length;j++)
  		        {
  		            sb.append("."+list.get(i)[j]);
  		        }
  		        io.println(sb.toString());
  		    }
  		    test--;
  		}
  		io.close();
  	}
  }
   
   class FastIO extends PrintWriter {
  	private InputStream stream;
  	private byte[] buf = new byte[1<<16];
  	private int curChar, numChars;
   
  	// standard input
  	public FastIO() { this(System.in,System.out); }
  	public FastIO(InputStream i, OutputStream o) {
  		super(o);
  		stream = i;
  	}
  	// file input
  	public FastIO(String i, String o) throws IOException {
  		super(new FileWriter(o));
  		stream = new FileInputStream(i);
  	}
   
  	// throws InputMismatchException() if previously detected end of file
  	private int nextByte() {
  		if (numChars == -1) throw new InputMismatchException();
  		if (curChar >= numChars) {
  			curChar = 0;
  			try {
  				numChars = stream.read(buf);
  			} catch (IOException e) {
  				throw new InputMismatchException();
  			}
  			if (numChars == -1) return -1; // end of file
  		}
  		return buf[curChar++];
  	}
   
  	public String nextLine() {
  		int c; do { c = nextByte(); } while (c <= '\n');
  		StringBuilder res = new StringBuilder();
  		do { res.appendCodePoint(c); c = nextByte(); } while (c > '\n');
  		return res.toString();
  	}
   
  	public String next() {
  		int c; do { c = nextByte(); } while (c <= ' ');
  		StringBuilder res = new StringBuilder();
  		do { res.appendCodePoint(c); c = nextByte(); } while (c > ' ');
  		return res.toString();
  	}
   
  	public int nextInt() { 
  		int c; do { c = nextByte(); } while (c <= ' ');
  		int sgn = 1; if (c == '-') { sgn = -1; c = nextByte(); }
  		int res = 0;
  		do {
  			if (c < '0' || c > '9')
  				throw new InputMismatchException();
  			res = 10*res+c-'0';
  			c = nextByte();
  		} while (c > ' ');
  		return res * sgn;
  	}
   
    public long nextLong() { 
  		int c; do { c = nextByte(); } while (c <= ' ');
  		long sgn = 1; if (c == '-') { sgn = -1; c = nextByte(); }
  		long res = 0;
  		do {
  			if (c < '0' || c > '9')
  				throw new InputMismatchException();
  			res = 10*res+c-'0';
  			c = nextByte();
  		} while (c > ' ');
  		return res * sgn;
  	}
   
  	public double nextDouble() { return Double.parseDouble(next()); }
  }