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% Document Info
\author{Jianmin Feng (taotao)}
\pdfinfo{
  /Title (java-recursive.pdf)
  /Creator (Cheatography)
  /Author (Jianmin Feng (taotao))
  /Subject (Java Recursive Cheat Sheet)
}

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        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
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\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{Java Recursive Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Jianmin Feng (taotao)} via \textcolor{DarkBackground}{\uline{cheatography.com/79308/cs/19302/}}}
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  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}Jianmin Feng (taotao) \\
  \uline{cheatography.com/taotao} \\
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  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 9th April, 2019.\\
   Page {\thepage} of \pageref{LastPage}.
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  Measure your website readability!\\
  www.readability-score.com
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\begin{document}
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\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Recursive method}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{a process is defined in terms of a simplier case of itself} \tn 
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\mymulticolumn{1}{x{5.377cm}}{each time local variable created and push into memory stack} \tn 
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\mymulticolumn{1}{x{5.377cm}}{when termination triggered, program return and completer most recent invocation (FILO) therefore reversed from call sequence.} \tn 
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\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\mymulticolumn{1}{x{5.377cm}}{Recursive could be very inefficient; it is for simplicity and beauty of code/thinking, not for efficient.}  \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Structure}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{public void recursiveMethod( ...) \{... \newline    if (base case) \{ ... \} //termination condition \newline    else \{ //non base case move algorithm to base \newline       ... \newline       recursiveMethod(...); //recursive call \newline       ... \newline    \} \newline \}} \tn 
\hhline{>{\arrayrulecolor{DarkBackground}}-}
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\mymulticolumn{1}{x{5.377cm}}{a tail recursive: there is no statement after recursive call.}  \tn 
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\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Recursive vs Iterative}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Every recursive algorithm can be written iteratively which is more efficient in time and memory.} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Recursive for elegance and simplicity of code} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Rule for recursion} \tn 
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\mymulticolumn{1}{x{5.377cm}}{1 Avaoid when involving large local array( memory overflow)} \tn 
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\mymulticolumn{1}{x{5.377cm}}{2 avoid for simple iterative method like factorial,fibonacci and linear search.} \tn 
% Row Count 8 (+ 2)
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\mymulticolumn{1}{x{5.377cm}}{3 use recursive when significantly simplify code} \tn 
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\mymulticolumn{1}{x{5.377cm}}{4 use recursive for divide and conquer problem(merge /binary sort) and branching process like traversing trees or directories} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Recursive help methods}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Private recursive method + public non recursive driver method (helper method)} \tn 
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\mymulticolumn{1}{x{5.377cm}}{Hide implementation of recursive from user + enhance efficiency by putting preconditions in helper method instead of in recursive method} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Driver method example1}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{//recursive method \newline private static int sum(int n)\{ \newline     if (n==1) return 1; \newline     else return n +sum(n-1); \newline \} \newline //Drive method \newline public static int getSum(int n) \{ \newline     if (n\textgreater{}0) return sum(n); \newline     else throw new IllegalArgumentException \newline                   ("Error: n must be positive"); \newline \}} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Driver method example 2}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{//recursive method \newline private boolean recurSearch \newline     (String{[}{]} a,int startIdx,String Key)\{ \newline     if (startIdx =a.length) return false; \newline     else if ( a{[}startIdx{]}.compareTo(key)==0)  \newline           return true; \newline     else return recurSearch(a,startIdx,key); \newline \} \newline //driver method \newline public boolean search( \newline     String{[}{]} a, String key) \newline \{  return recurSearch(a,0,key);\}} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Recursion in 2 dimensional grid}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{check the starting position is not out of ranger \newline     if condition met,   \newline         perform some action to solve problem \newline         recursiveCall(row+1,col) \newline         recursiveCall(row-1,col) \newline         recursiveCall(row,   col+1) \newline         recursiveCall(row,   col-1)} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Practice ...}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{Practice more until the recursive thinking become a second nature of your mind. It is beauty and simplicity of problem solving.% Row Count 3 (+ 3)
} \tn 
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\begin{tabularx}{5.377cm}{X}
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\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Untangle the recursive call by Sketching}}  \tn
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\mymulticolumn{1}{x{5.377cm}}{untangle by repeating call} \tn 
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\mymulticolumn{1}{x{5.377cm}}{untangle by box diagrams} \tn 
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% That's all folks
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