用\Statex使其不占用行号即可。
\usepackage{algorithm}
\usepackage{algorithmicx}
\usepackage{algpseudocode}\begin{algorithm}
\caption{2333}\label{233}
\begin{algorithmic}[1]
\Statex \textbf{Input:} 233
\Statex \textbf{Output:} 23333
\State 2233
\end{algorithmic}
\end{algorithm}
参考文献：
https://tex.stackexchange.com/questions/355937/how-to-add-input-and-output-before-algorithm-procedure（这个不知道为啥不管用）
https://blog.csdn.net/lovehuishouzan/article/details/107905468