只是为了好玩,另一种选择:
\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\draw[thick] (0,0) grid (4,4);
\node[draw, circle,fill=red]at (2,2){};
\foreach \p in {(2,1),(2,3),(1,2),(3,2)}
\node[draw, circle,fill]at \p {};
\end{tikzpicture}
\end{document}