Added files

gcd/Makefile

@@ -0,0 +1,31 @@
+CXX := g++
+CFLAGS := -std=c++11 -m64 -Wall -Werror -Wextra -O3
+
+.PHONY: all
+all: bin/gcd
+
+bin:
+	@mkdir -v bin
+
+bin/gcd: src/gcd.cpp | check-cxx-works bin
+	@echo Compiling $<
+	@${CXX} ${CFLAGS} $^ -o $@
+
+.PHONY: install
+install: bin/gcd
+	@cp -v $^ /usr/bin
+
+.PHONY: uninstall
+uninstall: /usr/bin/gcd
+	@rm -v $^
+
+.PHONY: clean
+clean:
+	@rm -rfv bin
+
+.PHONY: mrproper
+mrproper: clean
+
+.PHONY: check-cxx-works
+check-cxx-works:
+	@${CXX} --version >/dev/null 2>&1 || (echo 'Please install a C++ compiler.' && exit 1)