CXXFLAGS := -std=c++11 -Wall -Wextra -O2

progs := $(patsubst %.cc,%,$(wildcard d*.cc))

.PHONY: all
all: $(addsuffix _output.txt,$(progs))

.PHONY: clean
clean:
	rm -f $(progs) $(addsuffix _test.txt,$(progs))

.PHONY: ok-%
ok-%: %_test.txt
	@cp -v $< $*_output.txt

.PHONY: test-%
test-%: %_output.txt

%_output.txt: %_test.txt
	@test -f $@ || (echo $*:; cat $<)
	@test -f $@ && (diff -u $@ $< && touch $@) || exit 0

$(addsuffix _test.txt,$(progs)): %_test.txt: % %_input.txt
	./$< < $*_input.txt > $@