Algorithm 1 The core code of PrefixSpan+
Input: Sequence dataset S, Threshold of support degree min_sup
Output: The set of frequent sequential pattern FS
1:	Scan S, count the support number of all the items with length = 1, and delete the items from S, of which the support degree is less than min_sup, then obtain S’. The set of length-1 sequential pattern P contains all the items that are satisfied with the required support degree.
2:	FS = P
3:	Extension(S’, P)
4:	For each $P_j\in P$, construct CMAP for $P_j$ from S’
5:	if $CMA{P}_i=CMA{P}_s=\varphi$
6:	return FS
7:	else
8:	if $CMA{P}_i\ne \varphi$, traverse $CMA{P}_i$
9:	extend all the items in $c{m}_i\left(j\right)$ to $P_j$ by i-extension, and obtain $P_j^i$
10:	if $CMA{P}_s\ne \varphi$, traverse $CMA{P}_s$
11:	extend all the items in $c{m}_s\left(j\right)$ to $P_j$ by s-extension, and obtain $P_j^s$
12:	$P_j{}^{\prime }=P_j^i\cup P_j^s$ // Property 3
13:	$P^{\prime }={\displaystyle {\sum }_j{P}_j{}^{\prime }}$, $FS=FS\cup P^{\prime }$
14:	Extension(S’, P’)