Four figures in one row in Overleaf

Question

I would like to add four figures into a single row but I am unable to do it. I tried a lot to figure out the error but still failed. At the moment, there is one figure on row 1, the second figure on row two, third figure and fourth figure are on row 4.

\begin{figure}
%\centering
    %\hfill
    \subfigure[Training         loss]{\includegraphics[width=0.25\linewidth]{images/all_vits.pdf}}
%\vspace{-4pt}
%\hfill
\subfigure[Accuracy]{\includegraphics[width=0.25\linewidth]{images/acc_vit.pdf}}

%
    %\vspace{-4pt}
    %\hfill
    %\caption{Comparison of pure ViTs and Convolutional ViTs %models.}
    %\vspace{-13pt}
    %\label{fig:ALLVITS}
%\end{figure}
%\begin{figure}
%\hfill
\subfigure[Training loss]{\includegraphics[width=0.25\linewidth]{images/ours_loss.pdf}}
%\vspace{-4pt}
%\hfill
\subfigure[Accuracy]{\includegraphics[width=0.25\linewidth]{images/ours_acc.pdf}}
%\vspace{-4pt}
%\hfill
%\caption{Comparison of our module integrates in O-PVT.}
\label{fig:OPVT}

\end{figure}

Answer 1

For more information see Figures: What is the difference between using subfig or subfigure. Make sure that the sum of the width is less than 100 %. BTW, your code looks kind of messy. I recommend keeping it tidy, see the proposal below.

\documentclass{article}
\usepackage{graphicx}
\usepackage{subfig}
\begin{document}
\begin{figure}
\centering
\subfloat[First.]{\label{4figs-a} \includegraphics[width=0.20\textwidth]{example-image-a}}% The "%" masks the line break.
\hfill
\subfloat[Second.]{\label{4figs-b} \includegraphics[width=0.20\textwidth]{example-image-a}}%
\hfill
\subfloat[Third.]{\label{4figs-c} \includegraphics[width=0.20\textwidth]{example-image-a}}%
\hfill
\subfloat[Forth.]{\label{4figs-d} \includegraphics[width=0.20\textwidth]{example-image-a}}%
\caption{Four sub-floats.}
\label{4figs}
\end{figure}
See \figurename~\ref{4figs-b} and \figurename~\ref{4figs-d}.
\end{document}

Answer 2

In my case, the below code is worked fine.

\begin{figure}[t]
    \subfigure[Training loss curves]{\includegraphics[width=0.245\linewidth]{images/all.pdf}}
    \subfigure[Accuracy curves]{\includegraphics[width=0.245\linewidth]{images/all.pdf}}
    \label{fig:ALLVITS}
    \subfigure[Training loss curves]{\includegraphics[width=0.245\linewidth]{images/all.pdf}}
    \subfigure[Accuracy curves]{\includegraphics[width=0.245\linewidth]{images/all.pdf}}
    \caption{Comparison of our module integrates in O-PVT.}
    \label{fig:OPVT}
\end{figure}