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