Initialize array C of size $2$n

$2.$ i $0$

$3.$ j $0$

$4.$ S$0$ Comment: S$$ will count swaps; the answer lines below which you have to add will be

responsible for changing S$.$

$5.$ While $($i $<$ n OR j $<$ n$)$

$($a$)$ if j $=$ n or A$[$i$]<$ B$[$j$]$ :

$$ S$+=$ j

$$ set next element of C to A$[$i$]$

$($formally$,$ C$[$i $+$ j$]$ A$[$i$])$

$$ i $$ i$+1$

$($b$)$ if i $=$ n or A$[$i$]>$ B$[$j$]$:

$$ C$[$i$+$j$]=$ B$[$j$]$

$$ j $+=1$

$$ set next element of C to B$[$j