\documentclass[a4paper,10pt]{article}
\usepackage{myXsim}
\usepackage{pgfplots}
\pgfplotsset{compat = newest}
\usepgfplotslibrary{external} 
\tikzexternalize

\author{Benjamin Bertrand}
\title{Fonctions tableaux - Exercices}
\date{2021-12-07}

\DeclareExerciseCollection[step=3]{banque}
\xsimsetup{
    collect,
}

\pagestyle{empty}

\begin{document}

\input{exercises.tex}
\setcounter{exercise}{2}
\printcollection{banque}
\vfill

\end{document}