72 lines
2.5 KiB
Java
72 lines
2.5 KiB
Java
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import edu.princeton.cs.introcs.StdIn;
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import edu.princeton.cs.introcs.StdOut;
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/*************************************************************************
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* Compilation: javac TopM.java
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* Execution: java TopM M < input.txt
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* Dependencies: MinPQ.java Transaction.java StdIn.java StdOut.java
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* Data files: http://algs4.cs.princeton.edu/24pq/tinyBatch.txt
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*
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* Given an integer M from the command line and an input stream where
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* each line contains a String and a long value, this MinPQ client
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* prints the M lines whose numbers are the highest.
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*
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* % java TopM 5 < tinyBatch.txt
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* Thompson 2/27/2000 4747.08
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* vonNeumann 2/12/1994 4732.35
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* vonNeumann 1/11/1999 4409.74
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* Hoare 8/18/1992 4381.21
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* vonNeumann 3/26/2002 4121.85
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*
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*************************************************************************/
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/**
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* The TopM class provides a client that reads a sequence of
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* transactions from standard input and prints the M largest ones
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* to standard output. This implementation uses a {@link MinPQ} of size
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* at most M + 1 to identify the M largest transactions
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* and a {@link Stack} to output them in the proper order.
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*
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* For additional documentation, see <a href="http://algs4.cs.princeton.edu/24pq">Section 2.4</a>
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* of Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.
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*
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* @author Robert Sedgewick
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* @author Kevin Wayne
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*/
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public class TopM {
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// This class should not be instantiated.
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private TopM() { }
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/**
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* Reads a sequence of transactions from standard input; takes a
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* command-line integer M; prints to standard output the M largest
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* transactions in descending order.
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*/
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public static void main(String[] args) {
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int M = Integer.parseInt(args[0]);
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MinPQ<Transaction> pq = new MinPQ<Transaction>(M+1);
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while (StdIn.hasNextLine()) {
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// Create an entry from the next line and put on the PQ.
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String line = StdIn.readLine();
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Transaction transaction = new Transaction(line);
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pq.insert(transaction);
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// remove minimum if M+1 entries on the PQ
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if (pq.size() > M)
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pq.delMin();
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} // top M entries are on the PQ
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// print entries on PQ in reverse order
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Stack<Transaction> stack = new Stack<Transaction>();
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for (Transaction transaction : pq)
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stack.push(transaction);
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for (Transaction transaction : stack)
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StdOut.println(transaction);
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}
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}
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