\begin{tikzpicture}[scale=1.3]
	\path[fill=gray!20] (1,0) rectangle (2,1) node[pos=.5, color=black] {\scriptsize $w(2,1)$};
	\path[fill=gray!20] (2,0) rectangle (3,1) node[pos=.5, color=black] {\scriptsize $w(3,1)$};
	\path[fill=gray!20] (3,0) rectangle (4,1) node[pos=.5, color=black] {\scriptsize $w(4,1)$};
	\path[fill=gray!20] (2,1) rectangle (3,2) node[pos=.5, color=black] {\scriptsize $w(3,2)$};
	\path[fill=gray!20] (3,1) rectangle (4,2) node[pos=.5, color=black] {\scriptsize $w(4,2)$};
	\draw[->,>=latex] (0,-0.5) -- (0,2.5);
	\draw[->,>=latex] (-0.5,0) -- (4.5,0);
	\foreach \x in {0,...,4}
	\draw[dotted] (\x,0)--(\x,2);
	\foreach \y in {0,...,2}
	\draw[dotted] (0,\y)--(4,\y);
	\draw[line width=2pt,->,>=latex, shorten >=2pt,myblue] (0,0) -- (1,0) -- (1,1)--(2,1) -- (2,2)--(3,2)--(4,2);
	\foreach \x in {0,...,4}
	\foreach \y in {0,...,2}
	\draw[fill=black](\x,\y)circle(2pt);
	\node[above,myblue] at (0.5,0) {\scriptsize $W(1,0)$};	
	\node[above,myblue] at (1.5,1) {\scriptsize $W(2,1)$};	
	\node[above,myblue] at (2.5,2) {\scriptsize $W(3,2)$};	
	\node[above,myblue] at (3.5,2) {\scriptsize $W(4,2)$};		
	\node[left,myblue] at (1,0.6) {\scriptsize $1$};
	\node[left,myblue] at (2,1.6) {\scriptsize $1$};	
	\node[above left] at (0,0) {$(0,0)$};
\end{tikzpicture}