Finish assignment 3

Makefile

@@ -3,11 +3,14 @@ all: parse
 parser.cpp parser.hpp: parser.y
 	bison -d -o parser.cpp parser.y
 
+tree.o: tree.cpp
+	g++ -g -c -o tree.o tree.cpp
+
 scanner.cpp: scanner.l
 	flex -o scanner.cpp scanner.l
 
-parse: main.cpp parser.cpp scanner.cpp
-	g++ main.cpp parser.cpp scanner.cpp -o parse
+parse: main.cpp parser.cpp scanner.cpp tree.o
+	g++ -g main.cpp parser.cpp scanner.cpp tree.o -o parse
 
 clean:
-	rm -f parse scanner.cpp parser.cpp parser.hpp
+	rm -f parse scanner.cpp parser.cpp parser.hpp tree.o