《算法》第三章部分程序 part 5

▶ 书中第三章部分程序，加上自己补充的代码，包含公共符号表、集合类型

● 公共符号表，用于普通查找表的基本类

package package01;

import java.util.NoSuchElementException;
import java.util.TreeMap;
import edu.princeton.cs.algs4.StdIn;
import edu.princeton.cs.algs4.StdOut;

public class class01<Key extends Comparable<Key>, Value> implements Iterable<Key>
{
    private TreeMap<Key, Value> st;

    public class01()
    {
        st = new TreeMap<Key, Value>();
    }

    public Value get(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<get> key == null.
");
        return st.get(key);
    }

    public void put(Key key, Value val)
    {
        if (key == null)
            throw new IllegalArgumentException("
<put> key == null.
");
        if (val == null)
            st.remove(key);
        else
            st.put(key, val);
    }

    public void delete(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<delete> key == null.
");
        st.remove(key);
    }

    public boolean contains(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<contains> key == null.
");
        return st.containsKey(key);
    }

    public int size()
    {
        return st.size();
    }

    public boolean isEmpty()
    {
        return size() == 0;
    }

    public Iterable<Key> keys()
    {
        return st.keySet();
    }

    public Key min()
    {
        if (isEmpty())
            throw new NoSuchElementException("
<min> empty.
");
        return st.firstKey();
    }

    public Key max()
    {
        if (isEmpty())
            throw new NoSuchElementException("
<max> empty.
");
        return st.lastKey();
    }

    public Key ceiling(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<min> key == null.
");
        Key k = st.ceilingKey(key);
        if (k == null)
            throw new NoSuchElementException("
<min> k == null.
");
        return k;
    }

    public Key floor(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<min> key == null.
");
        Key k = st.floorKey(key);
        if (k == null)
            throw new NoSuchElementException("
<min> k == null.
");
        return k;
    }

    public static void main(String[] args)
    {
        class01<String, Integer> st = new class01<String, Integer>();
        for (int i = 0; !StdIn.isEmpty(); i++)
        {
            String key = StdIn.readString();
            st.put(key, i);
        }
        for (String s : st.keys())
            StdOut.println(s + " " + st.get(s));
    }
}

● 集合类型

package package01;

import java.util.NoSuchElementException;
import java.util.Iterator;
import java.util.TreeSet;
import edu.princeton.cs.algs4.StdOut;

public class class01<Key extends Comparable<Key>> implements Iterable<Key>
{
    private TreeSet<Key> set;

    public class01()
    {
        set = new TreeSet<Key>();
    }

    public class01(class01<Key> x)
    {
        set = new TreeSet<Key>(x.set);
    }

    public void add(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<add> key == null.
");
        set.add(key);
    }

    public boolean contains(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<contains> key == null.
");
        return set.contains(key);
    }

    public void delete(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<delete> key == null.
");
        set.remove(key);
    }

    public int size()
    {
        return set.size();
    }

    public boolean isEmpty()
    {
        return size() == 0;
    }

    public Iterator<Key> iterator()
    {
        return set.iterator();
    }

    public Key max()
    {
        if (isEmpty())
            throw new NoSuchElementException("
<max> empty.
");
        return set.last();
    }

    public Key min()
    {
        if (isEmpty())
            throw new NoSuchElementException("
<min> key == null.
");
        return set.first();
    }

    public Key ceiling(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<ceiling> key == null.
");
        Key k = set.ceiling(key);
        if (k == null)
            throw new NoSuchElementException("
<ceiling> k == null.
");
        return k;
    }

    public Key floor(Key key)
    {
        if (key == null)
            throw new IllegalArgumentException("
<floor> key == null.
");
        Key k = set.floor(key);
        if (k == null)
            throw new NoSuchElementException("
<floor> k == null.
");
        return k;
    }

    public class01<Key> union(class01<Key> that)
    {
        if (that == null)
            throw new IllegalArgumentException("
<floor> key == null.
");
        class01<Key> c = new class01<Key>();
        for (Key x : this)
            c.add(x);
        for (Key x : that)
            c.add(x);
        return c;
    }

    public class01<Key> intersects(class01<Key> that)
    {
        if (that == null)
            throw new IllegalArgumentException("
<floor> key == null.
");
        class01<Key> c = new class01<Key>();
        if (size() < that.size())          // 遍历较小的集合，去较大的集合中匹配，无所谓？
        {
            for (Key x : this)
            {
                if (that.contains(x))
                    c.add(x);
            }
        }
        else
        {
            for (Key x : that)
            {
                if (contains(x))
                    c.add(x);
            }
        }
        return c;
    }

    public boolean equals(Object other)
    {
        if (other == this)
            return true;
        if (other == null)
            return false;
        if (other.getClass() != getClass())
            return false;
        class01 that = (class01) other;
        return set.equals(that.set);
    }

    @Override
    public int hashCode()
    {
        throw new UnsupportedOperationException("
<hashCode> hashCode() not supported,
");
    }

    @Override
    public String toString()                    // 把集合的元素放进大括号中列出
    {
        String s = set.toString();
        return "{ " + s.substring(1, s.length() - 1) + " }";
    }

    public static void main(String[] args)
    {
        class01<String> set = new class01<String>();
        StdOut.println("set = " + set);     // 输出空集合

        set.add("www.cs.princeton.edu");    // 插入一些元素用于测试方法
        set.add("www.cs.princeton.edu");
        set.add("www.princeton.edu");
        set.add("www.math.princeton.edu");
        set.add("www.yale.edu");
        set.add("www.amazon.com");
        set.add("www.simpsons.com");
        set.add("www.stanford.edu");
        set.add("www.google.com");
        set.add("www.ibm.com");
        set.add("www.apple.com");
        set.add("www.slashdot.com");
        set.add("www.whitehouse.gov");
        set.add("www.espn.com");
        set.add("www.snopes.com");
        set.add("www.movies.com");
        set.add("www.cnn.com");
        set.add("www.iitb.ac.in");

        StdOut.println(set.contains("www.cs.princeton.edu"));
        StdOut.println(!set.contains("www.harvardsucks.com"));
        StdOut.println();
        StdOut.println("ceiling(www.simpsonr.com) = " + set.ceiling("www.simpsonr.com"));
        StdOut.println("ceiling(www.simpsons.com) = " + set.ceiling("www.simpsons.com"));
        StdOut.println("floor(www.simpsonr.com)   = " + set.floor("www.simpsonr.com"));
        StdOut.println("floor(www.simpsons.com)   = " + set.floor("www.simpsons.com"));
        StdOut.println();
        StdOut.println("set = " + set);
        StdOut.println();
        for (String s : set)                // 直接列出表中元素
            StdOut.println(s);
        StdOut.println();
        class01<String> set2 = new class01<String>(set);
        StdOut.println(set.equals(set2));
    }
}