diff options
| -rw-r--r-- | prolog/problems/lists/del_3/common.py | 5 | ||||
| -rw-r--r-- | prolog/problems/lists/del_3/sl.py | 8 |
2 files changed, 13 insertions, 0 deletions
diff --git a/prolog/problems/lists/del_3/common.py b/prolog/problems/lists/del_3/common.py index 125ece1..65c51d1 100644 --- a/prolog/problems/lists/del_3/common.py +++ b/prolog/problems/lists/del_3/common.py @@ -28,6 +28,7 @@ hint_type = { 'del_from_empty_list_success': Hint('del_from_empty_list_success'), 'lost_heads': Hint('lost_heads'), 'recursive_case': Hint('recursive_case'), + 'leading_heads_all_x': Hint('leading_heads_all_x'), } test_cases = [ @@ -95,6 +96,10 @@ def hint(code, aux_code): if prolog.engine.ask_truth(engine_id, 'del(q, [a,b,c,d,q,x,y,z], [x,y,z])'): return [{'id': 'lost_heads'}] + # used [X|T] instead of more general [H|T] in recursive case + if prolog.engine.ask_truth(engine_id, 'del(q, [a,b,c,d,q,x,y,z], [x,y,z])'): + return [{'id': 'leading_heads_all_x'}] + # L=[H|T] at the end of the rule; this can be detected with test cases and can be wrong (in some sense) # TODO: implement it, and provide a good explanation (might be hard) diff --git a/prolog/problems/lists/del_3/sl.py b/prolog/problems/lists/del_3/sl.py index ce82732..df5e014 100644 --- a/prolog/problems/lists/del_3/sl.py +++ b/prolog/problems/lists/del_3/sl.py @@ -80,6 +80,14 @@ Si pozabil dati glavo nazaj na začetek seznama, ko se vračaš iz rekurzije?</p <p><code>?- del(d, [a,b,c,d,e,f,g], L).</code></p> ''', + 'leading_heads_all_x': '''\ +<p>Si morda pozabil (copy/paste?) in uporabil <code>[X|T]</code> namesto bolj splošnega +<code>[H|T]</code> v rekurzivnem primeru?</p> +<p>Od spodnjih dveh vprašanj prologu prvo deluje, drugo pa ne.</p> +<p><code>?- del(d, [d,d,d,d,e,f,g], L).</code></p> +<p><code>?- del(d, [a,b,c,d,e,f,g], L).</code></p> +''', + 'final_hint': '''\ <p>Zanimivost: operaciji vstavljanja in brisanja iz seznama sta si ravno nasprotni. Če se malce poigraš z argumenti, lahko <code>del/3</code> rešiš kar z <code>insert/3</code>.</p> |