My Homework Template

homework.sty

%% Style for homework

\NeedsTeXFormat{LaTeX2e}[1994/06/01]
\ProvidesPackage{homework}

\RequirePackage{fancyhdr,enumerate}
\RequirePackage[margin=1in]{geometry}
\RequirePackage{amsmath,amsthm,amssymb,tikz}
\usetikzlibrary{calc,trees,positioning,arrows,fit,shapes}

\makeatletter
\renewcommand*\env@matrix[1][*\c@MaxMatrixCols c]{%
  \hskip -\arraycolsep
  \let\@ifnextchar\new@ifnextchar
  \array{#1}}
\makeatother

\newtheorem{lem}{Lemma}
\newenvironment{theorem}[2][Book Theorem]{\begin{trivlist}
\item[\hskip \labelsep {\bfseries #1}\hskip \labelsep {\bfseries #2.}]}{\end{trivlist}}
\newenvironment{exercise}[2][Exercise]{\begin{trivlist}
\item[\hskip \labelsep {\bfseries #1}\hskip \labelsep {\bfseries #2.}]}{\end{trivlist}}
\newenvironment{problem}[2][Problem]{\begin{trivlist}
\item[\hskip \labelsep {\bfseries #1}\hskip \labelsep {\bfseries #2.}]}{\end{trivlist}}

\makeatletter
\title{MAS477 \emph{Intro. to Graph Theory} Homework \HWNO} \let \Title \@title
\author{20120480 Jimin Park} \let \Author \@author
\makeatother

\setlength{\headheight}{15pt}
\lhead{\Author}\chead{\Title}\rhead{\today}
\lfoot{}\cfoot{\thepage}\rfoot{}
\pagestyle{fancy}

\renewcommand*{\proofname}{Solution}

\newcommand{\N}{\mathbb{N}}
\newcommand{\Z}{\mathbb{Z}}
\newcommand{\Q}{\mathbb{Q}}
\newcommand{\R}{\mathbb{R}}
\newcommand{\ep}{\epsilon}
\newcommand{\LRarr}{\Leftrightarrow}
\newcommand{\floor}[1]{\lfloor #1 \rfloor}
\newcommand{\lti}[1]{\lim_{#1 \to \infty}}
\newcommand{\ltni}[1]{\lim_{#1 \to -\infty}}
\newcommand{\AP}{Archimedes' principle}
\newcommand{\CS}{Cauchy sequence}
\newcommand{\BLANK}{.\\[160pt]}

\endinput