Add text under tikz rectangle

Question

I want to write some text under the rectangles drawn using tikz, to draw an array and its indices. Here is a mwe:

\documentclass[tikz,border=2mm]{standalone}
\usetikzlibrary{arrows, chains, fit, quotes}
\begin{document}
\begin{tikzpicture}
    \draw (0,0) rectangle (1,1) node[pos=.5] {$\#0$}; %node[anchor=north, pos=.5]{0};
    \draw (1,0) rectangle (2,1) node[pos=.5] {$\#0$};
    \draw (2,0) rectangle (3,1) node[pos=.5] {$\#1$};
    \draw (3,0) rectangle (4,1) node[pos=.5] {$\#2$};
    \draw (4,0) rectangle (5,1) node[pos=.5] {$\#1$};
    \foreach \x in {0,1,2,3,4}
        \draw (\x cm,0pt) -- (\x cm,0pt) node[anchor=north, pos=.5] {$\x$};
\end{tikzpicture}
\end{document}

Here is the result What I'd like to achieve is each number (those without #) centered under each box.

I also tried to use another node as in the comment, but can't manage to position it under the box and centered.

Answer 1

exploiting chains library and uses labels for text below nodes:

\documentclass[tikz,border=2mm]{standalone}
\usetikzlibrary{arrows, chains}

\begin{document}
    \begin{tikzpicture}[
  node distance = 0mm,
    start chain = going right,
     box/.style = {draw, semithick, minimum size=1cm, 
                   outer sep = 0mm, on chain}
                        ]
\foreach \i [count=\j from 0] in {\#0, \#0, \#1, \#2, \#1}
    \node[box,label=below:\j] {$\i$};
\end{tikzpicture}
\end{document}

Answer 2

You can create node under each box. This is a possible solution for your problem.

    \documentclass[border={10pt}]{standalone}

\usepackage{tikz}
\usetikzlibrary{positioning}

\begin{document}

\begin{tikzpicture}
    [%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        node distance=1mm,
        box/.style={rectangle,draw=black, ultra thick, minimum size=1cm},
    ]%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\foreach \y [count=\x from 0] in {\#0,\#0,\#1,\#2,\#1}
     \node[box] (\x) at (\x,0) {\y} node[below=of \x] {\x};

\end{tikzpicture}

\end{document}