Multiple chessboards in one line

Question

How would I place 4 chessboard side by side? Right now all of them are in one column, below each other. This is the code:

\documentclass[12pt, a4paper]{report}
\usepackage{ucs}
\usepackage[utf8x]{inputenc}
\usepackage{lmodern}
\usepackage[croatian]{babel}
\usepackage[margin=1.4in]{geometry}
\usepackage[labelsep=period]{caption}
\usepackage{graphicx}
\usepackage{mathastext}
\usepackage{textcomp}
\usepackage{amsthm}
\usepackage{amssymb}
\usepackage{afterpage}
\usepackage{amsmath}
\usepackage{mathtools}
\usepackage{epstopdf}
\usepackage{array}
\usepackage{tikz}
\usepackage{algorithm}  
\usepackage{algorithmic}
\usepackage{color, colortbl}
\usetikzlibrary{trees}
\usepackage{setspace}
\usepackage{hyperref}
\usepackage{listings}
\usepackage{multirow}
\usepackage{booktabs}
\usepackage[titletoc,page]{appendix}
\usepackage[up,bf,raggedright]{titlesec}
\usepackage{blindtext}
%\usepackage[dvipsnames]{xcolor}
\usepackage{keyval}
\definecolor{applegreen}{rgb}{0.55, 0.71, 0.0}
\definecolor{bananayellow}{rgb}{1.0, 0.88, 0.21}
\DeclarePairedDelimiter\ceil{\lceil}{\rceil}
\DeclarePairedDelimiter\floor{\lfloor}{\rfloor}


\begin{document}

        \def\Side{\ChessSide}
\newcommand\ChessBoxA{%
  {\fboxsep=0pt\fbox{\color{\ChessColori}\rule{\Side}{\Side}}}}
\newcommand\ChessBoxB{%
  {\fboxsep=0pt\fbox{\color{\ChessColorii}\rule{\Side}{\Side}}}}

\makeatletter
\newcommand\Row[1]{%
  \par\nobreak\nointerlineskip\vskip-\fboxrule%
  \@tfor\@tempa:=#1 \do {\csname ChessBox\@tempa\endcsname\kern-\fboxrule}}
\define@key{chessB}{side}{\def\ChessSide{#1}}
\define@key{chessB}{colori}{\def\ChessColori{#1}}
\define@key{chessB}{colorii}{\def\ChessColorii{#1}}
\setkeys{chessB}{
  side=1cm,
  colori=bananayellow,
  colorii=applegreen}
\makeatother
        \Conventional
        \begin{Chessboard}
\Row{A,A}
\Row{B,B}
\end{Chessboard}
\\[0.2 cm]
\makeatother
        \Conventional
        \begin{Chessboard}
\Row{B,A}
\Row{B,A}
\end{Chessboard}
\\[0.2 cm]
\makeatother
        \Conventional
        \begin{Chessboard}
\Row{A,B}
\Row{A,B}
\end{Chessboard}
\\[0.2 cm]
\makeatother
        \Conventional
        \begin{Chessboard}
\Row{B,B}
\Row{A,A}
\end{Chessboard}
\\[0.2 cm]
\makeatother
        \Conventional
        \begin{Chessboard}
\Row{A,B}
\Row{B,A}
\end{Chessboard}
\\[0.2 cm]
\makeatother
        \Conventional
        \begin{Chessboard}
\Row{B,A}
\Row{A,B}
\end{Chessboard}

\end{document}

Answer 1

Here's a prototype of what I understand you would like to do. From your code I kept only the essential parts.

The solution is based on the xcoffin package https://ctan.org/pkg/xcoffins?lang=en

that allow you to put material into boxes \SetVerticalCoffin and then precisely join them together. \JoinCoffins

The defined command \JoinAndPrintRow joins 4 boards in a single row and prints the row. The coffins can then be reused with new boards for the next row.

A somewhat longer explanation can be found at

Align text both horizontally and vertically

\documentclass[12pt, a4paper]{report}

\usepackage{graphicx}   
\usepackage{xcolor} 

\definecolor{applegreen}{rgb}{0.55, 0.71, 0.0}
\definecolor{bananayellow}{rgb}{1.0, 0.88, 0.21}

  \def\Side{\ChessSide}
\newcommand\ChessBoxA{%
    {\fboxsep=0pt\fbox{\color{\ChessColori}\rule{\Side}{\Side}}}}
\newcommand\ChessBoxB{%
    {\fboxsep=0pt\fbox{\color{\ChessColorii}\rule{\Side}{\Side}}}}

\makeatletter
\newcommand\Row[1]{%
    \par\nobreak\nointerlineskip\vskip-\fboxrule%
    \@tfor\@tempa:=#1 \do {\csname ChessBox\@tempa\endcsname\kern-\fboxrule}}
\define@key{chessB}{side}{\def\ChessSide{#1}}
\define@key{chessB}{colori}{\def\ChessColori{#1}}
\define@key{chessB}{colorii}{\def\ChessColorii{#1}}
\setkeys{chessB}{%
    side=1cm,
    colori=bananayellow,
    colorii=applegreen}
\makeatother

\usepackage{xcoffins} % added

\NewCoffin\Chessi
\NewCoffin\Chessii
\NewCoffin\Chessiii
\NewCoffin\Chessiv

\newcommand{\JoinAndPrintRow}{%
\JoinCoffins\Chessi[r,vc]\Chessii[l,vc]
\JoinCoffins\Chessi[r,vc]\Chessiii[l,vc]
\JoinCoffins\Chessi[r,vc]\Chessiv[l,vc]
\noindent\TypesetCoffin\Chessi
\vspace{2\baselineskip} 
}

\begin{document}
    
\SetVerticalCoffin\Chessi{0.25\textwidth}{\Row{A,A}\Row{B,B}}
\SetVerticalCoffin\Chessii{0.25\textwidth} {\Row{B,A}\Row{B,A}}
\SetVerticalCoffin\Chessiii{0.25\textwidth} {\Row{A,B}\Row{A,B}}
\SetVerticalCoffin\Chessiv{0.25\textwidth} {\Row{B,B}\Row{A,A}}

\JoinAndPrintRow % first row

\SetVerticalCoffin\Chessi{0.25\textwidth}{\Row{B,A}\Row{B,B}}
\SetVerticalCoffin\Chessii{0.25\textwidth} {\Row{A,A}\Row{B,A}}
\SetVerticalCoffin\Chessiii{0.25\textwidth} {\Row{A,B}\Row{B,B}}
\SetVerticalCoffin\Chessiv{0.25\textwidth} {\Row{B,A}\Row{A,A}}

\JoinAndPrintRow % second row
    
\end{document}