Add make init

Makefile

@@ -10,7 +10,12 @@ main: $(SOURCES:.cpp=.o)
 %.o: %.cpp
 	$(CPP) -o $@ -c $< $(INC)
 
-.PHONY: clean mrproper
+.PHONY: clean mrproper init
+
+init:
+	@echo '# please run the following command'
+	@echo '# source /dev/stdin <<< "$$(make init)"'
+	@echo 'export LD_LIBRARY_PATH=$$LD_LIBRARY_PATH:$(GUROBI_DIR)/lib'
 
 clean:
 	rm -f $(SOURCES:.cpp=.o)