What is the minimum number of parts required to split the sequence S to in order to obtain sequence T?
To get the sequence $T = \{4,7\}$ from $S = \{4,2,7,2\}$, you can take the entire set S as a minipart and remove $2$ from it. Therefore, there is just one minipart.

To get the sequence $T = \{4,7\}$ from $S = \{4,7,1,4,1,7,1\}$, you can take three minimarts as follows:

$P1 = \{4\}$
$P2 = \{7\}$
$P3 = \{1,4,1,7,1\}$

Now, remove $4$ from $P1$, remove $7$ from $P2$, and remove $1$ from $P3$. You will get the sequence $T = \{4,7\}$.