The de Bruijn graph is a directed graph used for representing overlapping strings in a collection of k-mers.
Given a set$S$ containing DNA strings of length $k+1$,
the de Bruijn graph $B$ corresponding to $S \cup S^{\textrm{rc}}$ (i.e., $S$ together with all possible
reverse complements of strings in $S$) is defined in the following way:
Create a node of $B$ for any length $k$substring of some $(k+1)$-mer in $S \cup S^{\textrm{rc}}$.
Do not form multiple nodes corresponding to the same DNA string.
Create a directed edge of $B$ connecting node $s$ to node $t$ if there is some $(k+1)$-mer $u$ in $S \cup S^{\textrm{rc}}$
whose prefix is $s$ and suffix is $t$. Label the directed edge with the $(k+1)$-mer $u$.
