mig33 Algorithm (1)

gistfile1.java

// Write java program that:
// takes its input from two files and prints out lines that exists in both files
package mig33;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

public class Problem1 {

  private static Set<Integer> lineHashes(String filePath) throws IOException {
    BufferedReader r = new BufferedReader(new InputStreamReader(
        new FileInputStream(new File(filePath))));
    Set<Integer> hashes = new HashSet<Integer>();
    String line = null;
    while ((line = r.readLine()) != null) {
      hashes.add(line.hashCode());
    }
    r.close();
    return hashes;
  }

  public static void main(String[] args) throws IOException {

    // extract hashes from file1
    Set<Integer> hashes1 = lineHashes(args[0]);

    BufferedReader r2 = new BufferedReader(new InputStreamReader(
        new FileInputStream(new File(args[1]))));
    String line = null;
    Set<Integer> printedHashes = new HashSet<Integer>();
    while ((line = r2.readLine()) != null) {
      Integer hashCode = line.hashCode();
      if (hashes1.contains(hashCode) && !printedHashes.contains(hashCode)) {
        printedHashes.add(hashCode);
        System.out.println(line);
      }
    }
    r2.close();
  }
}

// takes its input from two files but prints out lines that are unique instead
package mig33;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

public class Problem2 {

  private static Map<Integer,String> extractLines(String filePath) throws IOException {
    BufferedReader r = new BufferedReader(new InputStreamReader(new FileInputStream(new File(filePath))));
    Map<Integer,String> lines = new HashMap<Integer, String>();
    String line = null;
    while ((line = r.readLine()) != null) {
      lines.put(line.hashCode(), line);
    }
    r.close();
    return lines;
  }
 
  private static void printUniques(Map<Integer,String> map1, Map<Integer,String> map2) {
    for (Integer hashCode : map1.keySet()) {
      if (!map2.containsKey(hashCode)) {
        System.out.println(map1.get(hashCode));
      }
    }
  }
 
  public static void main(String[] args) throws IOException {

    // read file 1 and store it hashes and value
    Map<Integer,String> lines1 = extractLines(args[0]);

    // read file 2 and store it hashes and value
    Map<Integer,String> lines2 = extractLines(args[1]);
   
    // print uniques from lines1
    printUniques(lines1,lines2);
   
    // print uniques from lines2
    printUniques(lines2,lines1);
  }
}

// takes its input from two files but prints only lines that exist in the first file but not in the second
package mig33;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

public class Problem3 {

  private static Set<Integer> lineHashes(String filePath) throws IOException {
    BufferedReader r = new BufferedReader(new InputStreamReader(new FileInputStream(new File(filePath))));
    Set<Integer> hashes = new HashSet<Integer>();
    String line = null;
    while ((line = r.readLine()) != null) {
      hashes.add(line.hashCode());
    }
    r.close();
    return hashes;
  }
 
  public static void main(String[] args) throws IOException {

    // extract hashes from file 2
    Set<Integer> hashes2 = lineHashes(args[1]);
   
    // print uniques from lines1
    BufferedReader r = new BufferedReader(new InputStreamReader(new FileInputStream(args[0])));
    String line = null;
    Set<Integer> printedHashes = new HashSet<Integer>();
    while ((line = r.readLine()) != null) {
      Integer hashCode = line.hashCode();
      if (!hashes2.contains(hashCode) &&
          !printedHashes.contains(hashCode)) {
        System.out.println(line);
        printedHashes.add(hashCode);
      }
    }
    r.close();
  }
}