用LaTeX优雅地书写伪代码：Algorithm2e简明指南

1. 准备

\usepackage[ruled,linesnumbered]{algorithm2e}

• ruled 是让标题显示在上面，否则算法的标题则在下面。
• linesnumbered 让算法中显示行号。
• 还可以添加 boxed， 让算法排版时插入在一个盒子里。

2. 基本语法

• 如果你不想让你的伪代码叫做 'Algorithm 编号'， 可以使用 \renewcommand{\algorithmcfname}{算法名} 命令来修改。

• 除了\If, \Else, \ElseIf之外，还有\uIf, \lIf, \uElse, \lElse, \uElseIf, \lElseIf等命令，他们的区别在于

• \If, \Else, \ElseIf都是会以end结尾
• \uIf, \uElse, \uElseIf, 是不以end结尾的块级元素
• \lIf, \lElse, \lElseIf 是不以end为结尾的行内元素
• 在If-else结构中，\eIf 自带else（即 if 和 else 共用一个 end），而只是用 \If 和 \Else 的话则会多出一个end给Else。

3. 例子

例子1

\def\SetClass{article}\documentclass{\SetClass}\usepackage[lined,boxed,commentsnumbered]{algorithm2e}\begin{document}\begin{algorithm}[H]  \SetAlgoLined  \KwData{this text}  \KwResult{how to write algorithm with \LaTeX2e }
  initialization\;  \While{not at end of this document}{    read current\;    \eIf{understand}{      go to next section\;      current section becomes this one\;      }{      go back to the beginning of current section\;      }    }  \caption{How to write algorithms}\end{algorithm}\end{document}

例子2

\def\SetClass{article}\documentclass{\SetClass}\usepackage[linesnumbered,lined,boxed,commentsnumbered]{algorithm2e}\begin{document}\IncMargin{1em}\begin{algorithm}  \SetKwData{Left}{left}\SetKwData{This}{this}\SetKwData{Up}{up}  \SetKwFunction{Union}{Union}\SetKwFunction{FindCompress}{FindCompress}  \SetKwInOut{Input}{input}\SetKwInOut{Output}{output}
  \Input{A bitmap $Im$ of size $w\times l$}  \Output{A partition of the bitmap}  \BlankLine  \emph{special treatment of the first line}\;  \For{$i\leftarrow 2$ \KwTo $l$}{    \emph{special treatment of the first element of line $i$}\;    \For{$j\leftarrow 2$ \KwTo $w$}{\label{forins}      \Left$\leftarrow$ \FindCompress{$Im[i,j-1]$}\;      \Up$\leftarrow$ \FindCompress{$Im[i-1,]$}\;      \This$\leftarrow$ \FindCompress{$Im[i,j]$}\;      \If(\tcp*[h]{O(\Left,\This)==1}){\Left compatible with \This}{\label{lt}        \lIf{\Left $<$ \This}{\Union{\Left,\This}}        \lElse{\Union{\This,\Left}}      }      \If(\tcp*[f]{O(\Up,\This)==1}){\Up compatible with \This}{\label{ut}        \lIf{\Up $<$ \This}{\Union{\Up,\This}}        \tcp{\This is put under \Up to keep tree as flat as possible}\label{cmt}        \lElse{\Union{\This,\Up}}\tcp*[h]{\This linked to \Up}\label{lelse}      }    }    \lForEach{element $e$ of the line $i$}{\FindCompress{p}}  }  \caption{disjoint decomposition}\label{algo_disjdecomp}\end{algorithm}\DecMargin{1em}\end{document}

例子3

\def\SetClass{article}\documentclass{\SetClass}\usepackage[ruled,linesnumbered]{algorithm2e}\begin{document}\begin{algorithm}\caption{Simulation-optimization heuristic}\label{algorithm}\KwData{current period $t$, initial inventory $I_{t-1}$, initial capital $B_{t-1}$, demand samples}\KwResult{Optimal order quantity $Q^{\ast}_{t}$}$r\leftarrow t$\;$\Delta B^{\ast}\leftarrow -\infty$\;\While{$\Delta B\leq \Delta B^{\ast}$ and $r\leq T$}{$Q\leftarrow\arg\max_{Q\geq 0}\Delta B^{Q}_{t,r}(I_{t-1},B_{t-1})$\;$\Delta B\leftarrow \Delta B^{Q}_{t,r}(I_{t-1},B_{t-1})/(r-t+1)$\;\If{$\Delta B\geq \Delta B^{\ast}$}{$Q^{\ast}\leftarrow Q$\;$\Delta B^{\ast}\leftarrow \Delta B$\;}$r\leftarrow r+1$\;}\end{algorithm}\end{document}

例子4

\SetKwRepeat{Do}{do}{while}

\Do{<结束条件>}{<执行命令>}

\documentclass{article}\usepackage[linesnumbered, ruled]{algorithm2e}\SetKwRepeat{Do}{do}{while}%\begin{document}
\begin{algorithm}[H]  \KwData{this text}  \KwResult{how to write algorithm with \LaTeX2e }  initialization\;  \While{not at end of this document}{    read current\;    \Repeat{this end condition}{      do these things\;    }    \eIf{understand}{      go to next section\;      current section becomes this one\;    }{      go back to the beginning of current section\;    }    \Do{this end condition}{      do these things\;    }  }  \caption{How to write algorithms}\end{algorithm}
\end{document}

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