In: Computer Science
Read the input one line at a time until you have read all lines. Now output these lines in the opposite order from which they were read..
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
public class Part12 {
/**
* Your code goes here - see Part0 for an example
* @param r the reader to read from
* @param w the writer to write to
* @throws IOException
*/
public static void doIt(BufferedReader r, PrintWriter
w) throws IOException {
// Your code goes here - see Part0
for an example
}
/**
* The driver. Open a BufferedReader and a PrintWriter,
either from System.in
* and System.out or from filenames specified on the
command line, then call doIt.
* @param args
*/
public static void main(String[] args) {
try {
BufferedReader
r;
PrintWriter
w;
if (args.length
== 0) {
r = new BufferedReader(new
InputStreamReader(System.in));
w = new PrintWriter(System.out);
} else if
(args.length == 1) {
r = new BufferedReader(new
FileReader(args[0]));
w = new PrintWriter(System.out);
} else {
r = new BufferedReader(new
FileReader(args[0]));
w = new PrintWriter(new
FileWriter(args[1]));
}
long start =
System.nanoTime();
doIt(r,
w);
w.flush();
long stop =
System.nanoTime();
System.out.println("Execution time: " + 1e-9 * (stop-start));
} catch (IOException e) {
System.err.println(e);
System.exit(-1);
}
}
}
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class Part0 {
/**
* Read lines one at a time from r. After reading all
lines, output
* all lines to w, outputting duplicate lines only
once. Note: the order
* of the output is unspecified and may have nothing to
do with the order
* that lines appear in r.
* @param r the reader to read from
* @param w the writer to write to
* @throws IOException
*/
public static void doIt(BufferedReader r, PrintWriter
w) throws IOException {
Set<String> s = new HashSet<>();
for (String line = r.readLine(); line != null; line =
r.readLine()) {
s.add(line);
}
for (String text : s) {
w.println(text);
}
}
/**
* The driver. Open a BufferedReader and a PrintWriter,
either from System.in
* and System.out or from filenames specified on the
command line, then call doIt.
* @param args
*/
public static void main(String[] args) {
try {
BufferedReader
r;
PrintWriter
w;
if (args.length
== 0) {
r = new BufferedReader(new
InputStreamReader(System.in));
w = new PrintWriter(System.out);
} else if
(args.length == 1) {
r = new BufferedReader(new
FileReader(args[0]));
w = new PrintWriter(System.out);
} else {
r = new BufferedReader(new
FileReader(args[0]));
w = new PrintWriter(new
FileWriter(args[1]));
}
long start =
System.nanoTime();
doIt(r,
w);
w.flush();
long stop =
System.nanoTime();
System.out.println("Execution time: " + 1e-9 * (stop-start));
} catch (IOException e) {
System.err.println(e);
System.exit(-1);
}
}
}
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class Part1 {
public static void doIt(BufferedReader r, PrintWriter w) throws IOException {
String line;
// create a linked list whose elements are String objects
LinkedList<String> allLines = new LinkedList<String>();
// read the file line by line
while((line = r.readLine()) != null) {
// remove whitespaces from the line
line = line.trim();
// if line has characters after removing whitespaces
// add the line to the linked list
if(!line.isEmpty()){
allLines.add(line + "\n");
}
}
// print the lines in reverse order
// i.e. traverse the linked list in reverse order
Iterator it = allLines.descendingIterator();
// while there are more elements
while(it.hasNext()) {
// write the element to stream
w.write((String)it.next());
}
}
public static void main(String[] args) {
try {
BufferedReader r;
PrintWriter w;
if (args.length == 0) {
r = new BufferedReader(new InputStreamReader(System.in));
w = new PrintWriter(System.out);
}
else if (args.length == 1) {
r = new BufferedReader(new FileReader(args[0]));
w = new PrintWriter(System.out);
}
else {
r = new BufferedReader(new FileReader(args[0]));
w = new PrintWriter(new FileWriter(args[1]));
}
long start = System.nanoTime();
doIt(r, w);
w.flush();
long stop = System.nanoTime();
System.out.println("Execution time: " + 1e-9 * (stop-start));
}
catch (IOException e) {
System.err.println(e);
System.exit(-1);
}
}
}