As contig numbers must always be from 1 to N, where N is the number of contigs, if we remove a particular contig, we need to ensure we still have contigs 1 to N-1. In thise case, deleting contig x, where x != N, will mean that we have a hole (at x) which can be filled by moving N down to x.
To illustrate in an algorithm we have the following; Given N contigs and a request to delete contig x.
io_delete_contigoperation goes as we're already assuming the data on this contig has gone elsewhere.
Hence it is important to remember that after an
contig numbers may not be the same as before the call.