Update Makefile

Makefile

@@ -1,2 +1,21 @@
-main: main.cpp
-  gcc main.cpp
+# Compiler
+CXX = g++
+
+# Compiler flags
+CXXFLAGS = -std=c++11 -Wall
+
+# Source file
+SRC = main.cpp
+
+# Executable name
+TARGET = main
+
+# Default target
+all: $(TARGET)
+
+$(TARGET): $(SRC)
+	$(CXX) $(CXXFLAGS) -o $@ $<
+
+# Clean
+clean:
+	rm -f $(TARGET)