1607094146 赵励志

[ZhaoLizz]

作业

BaseSort

package com.company.sort;

public abstract class BaseSort {
    public abstract void sort(Comparable[] a);

    /**
     * 前者小于后者时返回true
     */
    boolean less(Comparable v, Comparable w) {
        return v.compareTo(w) < 0;
    }

    /**
     * 交换Comparable数组下标为 i 和 j 的两个元素的值
     */
    void exch(Comparable[] a, int i, int j) {
        Comparable t = a[i];
        a[i] = a[j];
        a[j] = t;
    }

}

QuickSort

package com.company.sort;

public class QuickSort extends BaseSort {
    @Override
    public void sort(Comparable[] a) {
        sort(a, 0, a.length - 1);
    }

    public void sort(Comparable[] a, int lo, int hi) {
        if (hi <= lo)
            return;

        int j = partition(a, lo, hi);
        sort(a, lo, j - 1);
        sort(a, j + 1, hi);
    }

    /**
     * 获取数组在当前范围内的切分元素的下标
     */
    public int partition(Comparable[] a, int lo, int hi) {
        int i = lo;
        int j = hi + 1;
        Comparable v = a[lo];

        while (true) {
            while (less(a[++i], v))
                if (i == hi)
                    break;

            while (less(v, a[--j]))
                if (j == lo)
                    break;

            //i j 相遇
            if (i >= j)
                break;
            exch(a, i, j);
        }

        exch(a, lo, j);
        return j;
    }
}

InsertSort

package com.company.sort;

public class InsertSort extends BaseSort {

    /**
     * 基于插入排序的希尔排序
     * @param a
     */
    @Override
    public void sort(Comparable[] a) {
        int N = a.length;
        int h = 1;

        while (h < N / 3) {
            h = 3 * h + 1;
        }

        while (h >= 1) {
            for (int i = h; i < N; i++) {
                for (int j = i; j >= h && less(a[j], a[j - h]); j -= h) {
                    exch(a, j, j - h);
                }
            }
            h /= 3;
        }
    }
}

SelectSort

package com.company.sort;

public class SelectSort extends BaseSort {

    @Override
    public void sort(Comparable[] a) {
        int N = a.length;
        for (int i = 0; i < N; i++) {
            int min = i;
            for (int j = i + 1; j < N; j++) {
                if (less(a[j],a[min]))
                    min = j;
                exch(a, i, min);
            }
        }
    }
}

Factory

package com.company.sort;

import java.util.Arrays;

public class Factory {
    private BaseSort baseSort;

    public void setBaseSort(BaseSort baseSort) {
        this.baseSort = baseSort;
    }

    public void doSort(Comparable[] a) {
        baseSort.sort(a);
        System.out.println(Arrays.toString(a));
    }
}

Test

package com.company.sort;

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        Factory factory = new Factory();
        Scanner in = new Scanner(System.in);
        Comparable[] a = new Comparable[10];

        for (int i = 0; i < 10; i++) {
            a[i] = in.nextInt();
        }

        factory.setBaseSort(new QuickSort());
//        factory.doSort(a);

        factory.setBaseSort(new SelectSort());
//        factory.doSort(a);

        factory.setBaseSort(new InsertSort());
//        factory.doSort(a);

    }
}