diff options
Diffstat (limited to 'prolog/problems/dcg/expr_3/common.py')
-rw-r--r-- | prolog/problems/dcg/expr_3/common.py | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/prolog/problems/dcg/expr_3/common.py b/prolog/problems/dcg/expr_3/common.py new file mode 100644 index 0000000..daa5b31 --- /dev/null +++ b/prolog/problems/dcg/expr_3/common.py @@ -0,0 +1,24 @@ +id = 171 +group = 'dcg' +number = 78 +visible = False +facts = None + +solution = '''\ +expr(N) --> term171(N). +expr(N) --> term171(N1), [+], expr(N2), {N is N1 + N2}. + +term171(N) --> factor171(N). +term171(N) --> factor171(N1), [*], term171(N2), {N is N1 * N2}. + +factor171(N) --> number171(N). +factor171(N) --> ['('], expr(N), [')']. + +memb171(X, [X|_]). +memb171(X, [_|T]) :- + memb171(X, T). + +digit171(N) --> [N], { memb171(N, [0,1,2,3,4,5,6,7,8,9]) }. +number171(N) --> digit171(N). +number171(N) --> number171(N1), digit171(D), { N is 10*N1 + D }. +''' |