51 lines
8.0 KiB
Plaintext
51 lines
8.0 KiB
Plaintext
\begin{Verbatim}[commandchars=\\\{\},codes={\catcode`\$=3\catcode`\^=7\catcode`\_=8\relax}]
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\PYG{c+c1}{// class to implement method 3 }
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\PYG{k+kd}{public}\PYG{+w}{ }\PYG{k+kd}{class} \PYG{n+nc}{StackVSQueue}\PYG{+w}{ }\PYG{k+kd}{implements}\PYG{+w}{ }\PYG{n}{PalindromeChecker}\PYG{+w}{ }\PYG{p}{\PYGZob{}}
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\PYG{+w}{ }\PYG{c+c1}{// method 3 - using a stack and a queue to do, essentially, what method 2 does (compare the first index to the last index, etc.)}
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\PYG{+w}{ }\PYG{n+nd}{@Override}
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\PYG{+w}{ }\PYG{k+kd}{public}\PYG{+w}{ }\PYG{k+kt}{boolean}\PYG{+w}{ }\PYG{n+nf}{checkPalindrome}\PYG{p}{(}\PYG{n}{String}\PYG{+w}{ }\PYG{n}{str}\PYG{p}{)}\PYG{+w}{ }\PYG{p}{\PYGZob{}}
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\PYG{+w}{ }\PYG{n}{ArrayStack}\PYG{+w}{ }\PYG{n}{stack}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{k}{new}\PYG{+w}{ }\PYG{n}{ArrayStack}\PYG{p}{();}\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{n}{ArrayQueue}\PYG{+w}{ }\PYG{n}{queue}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{k}{new}\PYG{+w}{ }\PYG{n}{ArrayQueue}\PYG{p}{();}\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{c+c1}{// looping through each character in the String and adding the character to the stack & queue }
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\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]++}\PYG{p}{;}
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\PYG{+w}{ }\PYG{k}{for}\PYG{+w}{ }\PYG{p}{(}\PYG{k+kt}{int}\PYG{+w}{ }\PYG{n}{i}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{l+m+mi}{0}\PYG{p}{;}\PYG{+w}{ }\PYG{n}{i}\PYG{+w}{ }\PYG{o}{\PYGZlt{}}\PYG{+w}{ }\PYG{n}{str}\PYG{p}{.}\PYG{n+na}{length}\PYG{p}{();}\PYG{+w}{ }\PYG{n}{i}\PYG{o}{++}\PYG{p}{)}\PYG{+w}{ }\PYG{p}{\PYGZob{}}
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\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{n}{stack}\PYG{p}{.}\PYG{n+na}{push}\PYG{p}{(}\PYG{n}{str}\PYG{p}{.}\PYG{n+na}{charAt}\PYG{p}{(}\PYG{n}{i}\PYG{p}{));}\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{n}{queue}\PYG{p}{.}\PYG{n+na}{enqueue}\PYG{p}{(}\PYG{n}{str}\PYG{p}{.}\PYG{n+na}{charAt}\PYG{p}{(}\PYG{n}{i}\PYG{p}{));}\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{p}{\PYGZcb{}}
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\PYG{+w}{ }\PYG{c+c1}{// looping through each character on the stack & queue and comparing them, returning false if they're different}
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\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]++}\PYG{p}{;}
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\PYG{+w}{ }\PYG{k}{for}\PYG{+w}{ }\PYG{p}{(}\PYG{k+kt}{int}\PYG{+w}{ }\PYG{n}{i}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{l+m+mi}{0}\PYG{p}{;}\PYG{+w}{ }\PYG{n}{i}\PYG{+w}{ }\PYG{o}{\PYGZlt{}}\PYG{+w}{ }\PYG{n}{str}\PYG{p}{.}\PYG{n+na}{length}\PYG{p}{();}\PYG{+w}{ }\PYG{n}{i}\PYG{o}{++}\PYG{p}{)}\PYG{+w}{ }\PYG{p}{\PYGZob{}}
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\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{1}\PYG{p}{;}
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\PYG{+w}{ }\PYG{k}{if}\PYG{+w}{ }\PYG{p}{(}\PYG{o}{!}\PYG{n}{stack}\PYG{p}{.}\PYG{n+na}{pop}\PYG{p}{().}\PYG{n+na}{equals}\PYG{p}{(}\PYG{n}{queue}\PYG{p}{.}\PYG{n+na}{front}\PYG{p}{()))}\PYG{+w}{ }\PYG{p}{\PYGZob{}}\PYG{+w}{ }
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\PYG{+w}{ }\PYG{k}{return}\PYG{+w}{ }\PYG{k+kc}{false}\PYG{p}{;}
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\PYG{+w}{ }\PYG{p}{\PYGZcb{}}
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\PYG{+w}{ }\PYG{c+c1}{// the complexity of ArrayQueue.dequeue() is 3n+2, where n is the number of items in the queue when dequeue() is called. }
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\PYG{+w}{ }\PYG{c+c1}{// we need to determine the number of items in the queue so that we can determine the number of primitive operations performed when queue.dequeue() is called.}
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\PYG{+w}{ }\PYG{c+c1}{// to do this, we'll loop through the queue, dequeuing each object and enqueueing it in another ArrayQueue. once complete, we'll reassign the variable queue to point to the new ArrayQueue containing all the objects}
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\PYG{+w}{ }\PYG{n}{ArrayQueue}\PYG{+w}{ }\PYG{n}{newQueue}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{k}{new}\PYG{+w}{ }\PYG{n}{ArrayQueue}\PYG{p}{();}\PYG{+w}{ }\PYG{c+c1}{// not counting the operations for this as it's not part of the algorithm, it's part of the operations counting}
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\PYG{+w}{ }\PYG{k+kt}{int}\PYG{+w}{ }\PYG{n}{n}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{l+m+mi}{0}\PYG{p}{;}\PYG{+w}{ }\PYG{c+c1}{// n is the number of items in the ArrayQueue when dequeue() is called}
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\PYG{+w}{ }\PYG{k}{while}\PYG{+w}{ }\PYG{p}{(}\PYG{o}{!}\PYG{n}{queue}\PYG{p}{.}\PYG{n+na}{isEmpty}\PYG{p}{())}\PYG{+w}{ }\PYG{p}{\PYGZob{}}
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\PYG{+w}{ }\PYG{n}{newQueue}\PYG{p}{.}\PYG{n+na}{enqueue}\PYG{p}{(}\PYG{n}{queue}\PYG{p}{.}\PYG{n+na}{dequeue}\PYG{p}{());}
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\PYG{+w}{ }\PYG{n}{n}\PYG{o}{++}\PYG{p}{;}
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\PYG{+w}{ }\PYG{p}{\PYGZcb{}}
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\PYG{+w}{ }
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\PYG{+w}{ }\PYG{n}{queue}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{n}{newQueue}\PYG{p}{;}\PYG{+w}{ }\PYG{c+c1}{// setting queue to point to the newQueue, which is just the state that queue would have been in if we didn't do this to calculate the primitive operations}
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\PYG{+w}{ }\PYG{n}{newQueue}\PYG{+w}{ }\PYG{o}{=}\PYG{+w}{ }\PYG{k+kc}{null}\PYG{p}{;}\PYG{+w}{ }\PYG{c+c1}{// don't need the newQueue object reference anymore}
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\PYG{+w}{ }
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\PYG{+w}{ }\PYG{n}{NewPalindrome}\PYG{p}{.}\PYG{n+na}{operations}\PYG{o}{[}\PYG{l+m+mi}{2}\PYG{o}{]}\PYG{+w}{ }\PYG{o}{+=}\PYG{+w}{ }\PYG{l+m+mi}{3}\PYG{o}{*}\PYG{n}{n}\PYG{+w}{ }\PYG{o}{+}\PYG{+w}{ }\PYG{l+m+mi}{2}\PYG{p}{;}\PYG{+w}{ }\PYG{c+c1}{// complexity of dequeue is 3n+2}
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\PYG{+w}{ }\PYG{n}{queue}\PYG{p}{.}\PYG{n+na}{dequeue}\PYG{p}{();}
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\PYG{+w}{ }\PYG{p}{\PYGZcb{}}
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\PYG{+w}{ }\PYG{k}{return}\PYG{+w}{ }\PYG{k+kc}{true}\PYG{p}{;}
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\PYG{+w}{ }\PYG{p}{\PYGZcb{}}
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\PYG{p}{\PYGZcb{}}
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\end{Verbatim}
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