アルゴ演習15-3

Algo15_ex3.java

/**
 * Created by @twinkfrag on 2015/09/26.
 */

import java.nio.file.*;
import java.util.*;
import java.io.*;
import java.util.stream.*;

/**
 * アルゴ演習15の課題に関して、解説とJava8などでの改良点
 * 問題に対する解答として間違っている可能性もあるので注意
 * <p>
 * 3週目
 */
public class Algo15_ex3 {
    public static void main(String[] args) {
        TestSort.main(args);
    }
}

abstract class SortableBase {
    protected int[] array;

    public SortableBase(String filename) {
        try (Stream<String> st = Files.lines(Paths.get(filename))) {
            array = st.mapToInt(Integer::parseInt).toArray();
        } catch (IOException | NumberFormatException e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    public abstract void sort();

    public void output(String filename) {
        List<String> outList = Arrays.stream(array).<String>mapToObj(String::valueOf).collect(Collectors.toList());

        try {
            Files.write(Paths.get(filename), outList);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class BubbleSort extends SortableBase {

    public BubbleSort(String filename) {
        super(filename);
    }

    @Override
    public void sort() {
        for (int i = 0; i < array.length; i++) {
            for (int j = array.length - 1; j > i; j--) {
                if (array[j] < array[i]) {
                    int temp = array[i];
                    array[i] = array[j];
                    array[j] = temp;
                }
            }
        }
    }
}

class SelectionSort extends SortableBase {

    public SelectionSort(String filename) {
        super(filename);
    }

    @Override
    public void sort() {
        for (int i = 0; i < array.length; i++) {
            int minIndex = i;
            for (int j = i + 1; j < array.length; j++) {
                if (array[j] < array[minIndex]) minIndex = j;
            }
            int temp = array[i];
            array[i] = array[minIndex];
            array[minIndex] = temp;
        }
    }
}

class InsertionSort extends SortableBase {

    public InsertionSort(String filename) {
        super(filename);
    }

    @Override
    public void sort() {
        for (int i = 1; i < array.length; i++) {
            for (int j = i; j > 0; j--) {
                if (array[j - 1] < array[j]) break;
                int temp = array[j - 1];
                array[j - 1] = array[j];
                array[j] = temp;
            }
        }
    }
}


class TestSort {
    public static void main(String[] args) {
        long start, stop;
        String file1 = "rand2.txt";
        String file2 = "sorted2.txt";
        String file3 = "reverse2.txt";
        String file4 = "same2.txt";

        List<String> files = Arrays.asList(file1, file2, file3, file4);
        files.forEach(filename -> {
            List<SortableBase> sorts = Arrays.asList(
                    new BubbleSort(filename),
                    new SelectionSort(filename),
                    new InsertionSort(filename)
            );

            System.out.println(String.format("%sのソート", filename));

            sorts.forEach(sort -> {
                long f = System.currentTimeMillis();
                sort.sort();
                long e = System.currentTimeMillis();
                System.out.println(String.format("%s : %d [ms]", sort.getClass().getName(), e - f));
            });
        });
    }
}