How can I have (a) (b) signs at the leftmost side of multiple tikz figures?

Question

I want to have following example format for two tikz figures, where (a) and (b) are located at most left side of them.

Example reference: Cormen/Introduction to Algorithms 2022 page: 341

Please note that I am only interested for placing (a), (b), (c), ... labels.

---

The solution I come up with is using How to label/tag TikZ diagrams?. But here I was not able to change equation numbers (2) to (a) and (3) to (b) , also I was not able to change their location to the most left hand side.

my tex code:

\documentclass{article}
\usepackage{tikz-cd}
\usepackage{blindtext}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\setcounter{page}{15}
\noindent
\begin{equation}
    \begin{tikzcd}
        x = 5 * 5; \
    \end{tikzcd}
\end{equation}
into a commutative diagramm
\begin{equation}
    \begin{tikzcd}
        B\times_A C \arrow{r}{\pi_2}\arrow{d}[swap]{\pi_1} & C\arrow{d}{g} \
        B \arrow{r}[swap]{f} & A;
    \end{tikzcd}
\end{equation}
\begin{equation}
    \begin{tikzpicture}[compute/.style={draw,thick,font=\sffamily,
            append after command={
                (\tikzlastnode.south west) edge[double=gray!50,double distance=3pt,
                line cap=rect,
                shorten >=-2pt,shorten <=-2pt]
                (\tikzlastnode.south east)}}]
        \node[compute] (n1) {Node};
        \node[compute,right=2cm of n1] (n2) {More text};
        \draw[thick,-stealth] (n1) -- (n2);
    \end{tikzpicture}
\end{equation}
\end{document}

output:

wanted output:

Answer 1

I'm guessing that you like to obtain the following:

Using @Andrew Swann answer you can write:

\documentclass{article}
\usepackage{lipsum}
\usepackage{amsmath}
\makeatletter
\newcommand{\leqnos}{\tagsleft@true\let\veqno@@leqno}
\newcommand{\reqnos}{\tagsleft@false\let\veqno@@eqno}
\reqnos
\makeatother
\newcounter{eqtn}
\usepackage{tikz-cd}
\usetikzlibrary{positioning}
\begin{document}
\setcounter{page}{15}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\lipsum[3][1-3]
\begingroup\leqnos
\setcounter{eqtn}{\theequation}
\setcounter{equation}{0}
\renewcommand\theequation{\alph{equation}}
\begin{equation}
    \begin{tikzcd}
        x = 5 * 5; \
    \end{tikzcd}
\end{equation}
into a commutative diagramm
\begin{equation}
    \begin{tikzcd}
        B\times_A C \arrow{r}{\pi_2}\arrow{d}[swap]{\pi_1} & C\arrow{d}{g} \
        B \arrow{r}[swap]{f} & A;
    \end{tikzcd}
\end{equation}
\begin{equation}
    \begin{tikzpicture}[compute/.style={draw,thick,font=\sffamily,
            append after command={
                (\tikzlastnode.south west) edge[double=gray!50,double distance=3pt,
                line cap=rect,
                shorten >=-2pt,shorten <=-2pt]
                (\tikzlastnode.south east)}}]
        \node[compute] (n1) {Node};
        \node[compute,right=2cm of n1] (n2) {More text};
        \draw[thick,-stealth] (n1) -- (n2);
    \end{tikzpicture}
\end{equation}
\setcounter{equation}{\theeqtn}
    \endgroup
\lipsum[66]
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\end{document}

I wonder, why you not use the sidcap package and use for example as

\begin{SCfigure}
\includegraphics{image}
\caption{A figure and its caption framed}
\label{fig:test}
\end{SCfigure}

and for them change caption numbering on the similar way as is done above.

Edit: Simpler code with manual tagging of equation:

\documentclass{article}
\usepackage{lipsum}
\usepackage{amsmath}
\makeatletter
\newcommand{\leqnos}{\tagsleft@true\let\veqno@@leqno}
\newcommand{\reqnos}{\tagsleft@false\let\veqno@@eqno}
\reqnos
\makeatother
\usepackage{tikz-cd}
\usetikzlibrary{positioning}
\begin{document}
\setcounter{page}{15}
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\lipsum[1][1-3]
\begingroup\leqnos
\begin{equation}
    \begin{tikzcd}
        x = 5 * 5;  \tag{a}\
    \end{tikzcd}
\end{equation}
into a commutative diagramm
\begin{equation}
    \begin{tikzcd}
        B\times_A C \arrow{r}{\pi_2}\arrow{d}[swap]{\pi_1} & C\arrow{d}{g} \
        B \arrow{r}[swap]{f} & A;
    \end{tikzcd}      \tag{b}
\end{equation}
\begin{equation}
    \begin{tikzpicture}[compute/.style={draw,thick,font=\sffamily,
            append after command={
                (\tikzlastnode.south west) edge[double=gray!50,double distance=3pt,
                line cap=rect,
                shorten >=-2pt,shorten <=-2pt]
                (\tikzlastnode.south east)}}]
        \node[compute] (n1) {Node};
        \node[compute,right=2cm of n1] (n2) {More text};
        \draw[thick,-stealth] (n1) -- (n2);
    \end{tikzpicture}     \tag{a}
\end{equation}
    \endgroup
\lipsum[66]
\begin{equation}
a^2 + b^2 = c^2
\end{equation}
\end{document}

Compilation result is the same as before.