diff --git a/huffman_coding/.project b/huffman_coding/.project
new file mode 100644
index 0000000..f022a5b
--- /dev/null
+++ b/huffman_coding/.project
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>huffman_coding</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+	<filteredResources>
+		<filter>
+			<id>1734357118166</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.core.resources.regexFilterMatcher</id>
+				<arguments>node_modules|\.git|__CREATED_BY_JAVA_LANGUAGE_SERVER__</arguments>
+			</matcher>
+		</filter>
+	</filteredResources>
+</projectDescription>
diff --git a/huffman_coding/.settings/org.eclipse.core.resources.prefs b/huffman_coding/.settings/org.eclipse.core.resources.prefs
new file mode 100644
index 0000000..99f26c0
--- /dev/null
+++ b/huffman_coding/.settings/org.eclipse.core.resources.prefs
@@ -0,0 +1,2 @@
+eclipse.preferences.version=1
+encoding/<project>=UTF-8
diff --git a/huffman_coding/.settings/org.eclipse.jdt.core.prefs b/huffman_coding/.settings/org.eclipse.jdt.core.prefs
new file mode 100644
index 0000000..9a7984b
--- /dev/null
+++ b/huffman_coding/.settings/org.eclipse.jdt.core.prefs
@@ -0,0 +1,11 @@
+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=21
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=21
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.release=enabled
+org.eclipse.jdt.core.compiler.source=21
diff --git a/huffman_coding/src/huffman_coding/Main.java b/huffman_coding/src/huffman_coding/Main.java
new file mode 100644
index 0000000..6b1f2c6
--- /dev/null
+++ b/huffman_coding/src/huffman_coding/Main.java
@@ -0,0 +1,46 @@
+package huffman_coding;
+
+import java.util.ArrayList;
+import tester.Tester;
+
+class Examples {
+
+    void testTest(Tester t) {
+        t.checkExpect(1, 1);
+    }
+}
+
+class Huffman {
+
+    ArrayList<String> charset; // Character set.
+    ArrayList<Boolean> freqs; // Relative frequencies of characters.
+
+    Huffman(ArrayList<String> charset, ArrayList<Boolean> 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."
+        );
+
+        this.charset = charset;
+        this.freqs = freqs;
+    }
+}
+
+// Binary tree.
+interface ITree<T> {}
+
+class Node<T> implements ITree<T> {
+
+    ITree<T> l;
+    ITree<T> r;
+
+    Node(ITree<T> l, ITree<T> r) {
+        this.l = l;
+        this.r = r;
+    }
+}
+
+class Leaf<T> implements ITree<T> {}