THings.

huffman_coding/src/huffman_coding/Main.java

@@ -1,28 +1,53 @@
 package huffman_coding;
 
 import java.util.ArrayList;
+import java.util.Arrays;
+
 import tester.Tester;
 
 class Examples {
+    ITree a;
+    ITree b;
+    ITree c;
+    ITree d;
+    ITree e;
+    ITree f;
 
-    void testTest(Tester t) {
-        t.checkExpect(1, 1);
+    ArrayList<ITree> trees;
+    ArrayList<ITree> treesSorted;
+
+    void init() {
+        a = new Leaf(12, "a");
+        b = new Leaf(45, "b");
+        c = new Leaf(5, "c");
+        d = new Leaf(13, "d");
+        e = new Leaf(9, "e");
+        f = new Leaf(16, "f");
+
+        trees = new ArrayList<ITree>(Arrays.asList(a, b, c, d, e, f));
+        treesSorted = new ArrayList<ITree>(Arrays.asList(c, e, a, d, f, b));
+    }
+
+    void testITreeSort(Tester t) {
+        init();
+        Util.sort(trees);
+        t.checkExpect(trees, treesSorted);
     }
 }
 
 class Huffman {
 
     ArrayList<String> charset; // Character set.
-    ArrayList<Boolean> freqs; // Relative frequencies of characters.
+    ArrayList<Integer> freqs; // Frequencies of characters.
 
-    Huffman(ArrayList<String> charset, ArrayList<Boolean> freqs) {
-        if (charset.size() != freqs.size()) throw new IllegalArgumentException(
-            "Character set must match frequencies."
-        );
+    Huffman(ArrayList<String> charset, ArrayList<Integer> freqs) {
+        if (charset.size() != freqs.size())
+            throw new IllegalArgumentException(
+                    "Character set must match frequencies.");
 
-        if (charset.size() < 2) throw new IllegalArgumentException(
-            "Character set too small."
-        );
+        if (charset.size() < 2)
+            throw new IllegalArgumentException(
+                    "Character set too small.");
 
         this.charset = charset;
         this.freqs = freqs;
@@ -30,17 +55,63 @@ class Huffman {
 }
 
 // Binary tree.
-interface ITree<T> {}
+interface ITree {
+    // Compare this and another tree, and return the lesser of the two.
+    ITree lesserOf(ITree n);
 
-class Node<T> implements ITree<T> {
+    // Is this tree less than the given frequency?
+    boolean lessThan(int freq);
+}
 
-    ITree<T> l;
-    ITree<T> r;
+abstract class ATree implements ITree {
+    int freq; // The frequency of the tree.
 
-    Node(ITree<T> l, ITree<T> r) {
+    ATree(int freq) {
+        this.freq = freq;
+    }
+
+    public ITree lesserOf(ITree n) {
+        return n.lessThan(this.freq) ? n : this;
+    }
+
+    public boolean lessThan(int freq) {
+        return this.freq < freq;
+    }
+}
+
+class Node extends ATree {
+
+    // Left and right branches of tree.
+    ITree l, r;
+
+    Node(int freq, ITree l, ITree r) {
+        super(freq);
         this.l = l;
         this.r = r;
     }
 }
 
-class Leaf<T> implements ITree<T> {}
+class Leaf extends ATree {
+    String ch; // The character.
+
+    Leaf(int freq, String ch) {
+        super(freq);
+        this.ch = ch;
+    }
+}
+
+class Util {
+    // Sort a list of trees from least to most frequent.
+    static void sort(ArrayList<ITree> trees) {
+
+    }
+
+    // Insert a Tree into an ArrayList of trees already sorted in [0, i], where
+    // 0 <= i <= sortedTrees.size(), such that it is sorted through [0, i].
+    static void insert(ITree tree, ArrayList<ITree> sortedTrees, int maxIndexPossible) {
+    }
+
+    // Insert a Tree in an already fully sorted ArrayList of Trees.
+    static void insert(ITree tree, ArrayList<ITree> sortedTrees) {
+    }
+}