Implemented count(), toString()

src/Tree.java

@@ -1,2 +1,114 @@
+import java.util.ArrayList;
+import java.util.Optional;
+
 public class Tree {
+
+
+    /**
+     * The person's name (family name last).
+     */
+    private Optional<Object> root;
+    /**
+     * The person's UTORid
+     */
+    ArrayList<Tree> subtrees;
+
+    /**
+     * Initialize this Person named name with UTORid utorid.
+     *
+     * @param root   the person's name (family name last)
+     * @param subtrees the person's UTORid
+     */
+    Tree (Optional<Object> root, ArrayList<Tree> subtrees) {
+        /** Initialize a new Tree with the given root value and subtrees.
+
+         If <root> is None, the tree is empty.
+         Precondition: if <root> is None, then <subtrees> is empty.
+         */
+
+        this.root = root;
+        if (subtrees == null) {
+            this.subtrees = new ArrayList<Tree>();
+
+        } else {
+            this.subtrees = new ArrayList<>(this.subtrees);
+
+        }
+
+
+    }
+
+
+    Tree () {
+        /** Initialize a new Tree with the given root value and subtrees.
+
+         If <root> is None, the tree is empty.
+         Precondition: if <root> is None, then <subtrees> is empty.
+         */
+
+        this.root = root;
+        this.subtrees = new ArrayList<Tree>();
+
+    }
+
+    boolean isEmpty() {
+        return this.root == null;
+    }
+
+    int size() {
+        if (this.isEmpty()) {
+            return 0;
+        } else {
+            int size = 1;
+            for (Tree subtree : this.subtrees) {
+                size += subtree.size();
+            }
+            return size;
+        }
+
+
+    }
+}
+public int count(Object item) {
+
+        if (this.is_empty()) {
+            return 0;
+        } else {
+
+            int num = 0;
+
+            if (this.root == item) {
+                num += 1;
+            }
+
+            for (Tree subtree : this.subtrees) {
+                num += subtree.count(item);
+            }
+
+            return num;
+        }
+    }
+
+    public String toString() {
+        return this.str_indented();
+    }
+
+    private String str_indented(int depth) {
+
+        if (this.is_empty()) {
+            return "";
+        } else {
+            String s = "  ".repeat(depth) + toString(this.root) + "\n";
+            for (Tree subtree : this.subtrees) {
+                s += subtree.str_indented(depth + 1);
+            }
+
+            return s;
+
+        }
+    }
+
+    private String str_indented() {
+        return this.str_indented(0);
+    }
 }