RosettaCodeData/Task/Percolation-Mean-cluster-density/J/percolation-mean-cluster-density-4.j

   idclust M
1 0 0 0 0 0
0 0 0 2 0 0
0 0 0 2 0 0
3 3 0 0 0 0
0 0 0 4 0 5
6 6 0 4 4 0
   (idclust M) {'.ABCDEFG'
A.....
...B..
...B..
CC....
...D.E
FF.DD.