improve Makefile

Makefile

@@ -1,6 +1,16 @@
-TARGETS = main
+TARGETS = main one-sided
 
 all: ${TARGETS}
 
-main: main.cpp
-	mpicxx -Wall -Wextra $< -o $@
+.PHONY: clean
+clean:
+	rm -f ${TARGETS} *.o
+
+MPICXX := mpicxx
+CXXFLAGS := -std=c++11 -Wall -Wextra -Wshadow -pedantic -O2
+
+main: main.cpp Makefile
+	$(MPICXX) $(CXXFLAGS) $< -o $@
+
+one-sided: one_sided.cpp Makefile
+	$(MPICXX) $(CXXFLAGS) $< -o $@