3 files changed, 105 insertions, 0 deletions
diff --git a/prolog/problems/world_data/flows_2/common.py b/prolog/problems/world_data/flows_2/common.py
new file mode 100644
index 0000000..a3cf79b
--- /dev/null
+++ b/prolog/problems/world_data/flows_2/common.py
@@ -0,0 +1,51 @@
+from operator import itemgetter
+import socket
+import prolog.engine
+import prolog.util
+from server.hints import Hint
+import server.problems
+
+id = 10009
+number = 90
+visible = True
+facts = 'mondial'
+
+solution = '''\
+flows(River, Sea) :-
+    river(River, _, _, Sea, _, _, _, _, _, _, _, _),
+    Sea \= null.
+flows(River, Sea) :-
+    river(River, River2, _, _, _, _, _, _, _, _, _, _),
+    River2 \= null,
+    flows(River2, Sea).
+'''
+
+hint_type = {
+}
+
+test_cases = [
+    ("flows('Rhone', X)", [{'X': "'Mediterranean Sea'"}]),
+    ("flows(X, 'Java Sea')", [{'X': "'Mahakam'"}, {'X': "'Barito'"}]),
+    ("flows('Drau', X)", [{'X': "'Black Sea'"}]),
+]
+
+def test(code, aux_code):
+    n_correct = 0
+    engine_id = None
+    try:
+        engine_id, output = prolog.engine.create(code=code+aux_code, timeout=5.0)
+        if engine_id is not None and 'error' not in map(itemgetter(0), output):
+            # Engine successfully created, and no syntax error in program.
+            for query, answers in test_cases:
+                if prolog.engine.check_answers(engine_id, query=query, answers=answers, timeout=2.0, inference_limit=None):
+                    n_correct += 1
+    except socket.timeout:
+        pass
+    finally:
+        if engine_id:
+            prolog.engine.destroy(engine_id)
+
+    hints = [{'id': 'test_results', 'args': {'passed': n_correct, 'total': len(test_cases)}}]
+    if n_correct == len(test_cases):
+        hints += [{'id': 'final_hint'}]
+    return n_correct, len(test_cases), hints
diff --git a/prolog/problems/world_data/flows_2/en.py b/prolog/problems/world_data/flows_2/en.py
new file mode 100644
index 0000000..f108001
--- /dev/null
+++ b/prolog/problems/world_data/flows_2/en.py
@@ -0,0 +1,20 @@
+name = 'flows/2'
+slug = ''
+
+description = '''\
+<p><code>flows(X, Y)</code>: the river <code>X</code> flows to sea <code>Y</code>.
+The predicate should follow the flow from <code>X</code> through different rivers
+until it reaches a sea - for example, Drina flows into Save, which flows into Donau,
+ending in the Black Sea:</p>
+<pre>
+?- flows('Drina', Y).
+  Y = 'Black Sea'.
+</pre>
+<p>River data is given by the predicate</p>
+<pre>
+river(Name, FlowsToRiver, FlowsToLake, FlowsToSea, Length, Area,
+      SourceLat, SourceLon, SourceElevation, MouthLat, MouthLon).
+</pre>
+'''
+
+hint = {}
diff --git a/prolog/problems/world_data/flows_2/sl.py b/prolog/problems/world_data/flows_2/sl.py
new file mode 100644
index 0000000..ef46f6b
--- /dev/null
+++ b/prolog/problems/world_data/flows_2/sl.py
@@ -0,0 +1,34 @@
+name = 'flows/2'
+slug = ''
+
+description = '''\
+<p><code>flows(X, Y)</code>: reka <code>X</code> se izliva v morje <code>Y</code>.
+Predikat naj sledi toku skozi različne reke - Drina se npr. priključi Savi,
+ki se priključi Donavi, ki teče v Črno morje, zato naj program odgovori tako:</p>
+<pre>
+?- flows('Drina', Y).
+  Y = 'Black Sea'.
+</pre>
+<p>Podatki o rekah so predstavljeni s predikatom</p>
+<pre>
+river(Name, FlowsToRiver, FlowsToLake, FlowsToSea, Length, Area,
+      SourceLat, SourceLon, SourceElevation, MouthLat, MouthLon).
+</pre>
+<p>Za vsako reko je podan največ en izmed argumentov <code>FlowsToRiver</code>,
+<code>FlowsToLake</code> in <code>FlowsToSea</code>, ki pove, v katero reko,
+jezero oziroma morje se izliva; ostala dva argumenta pa sta <code>null</code>.
+'''
+
+plan = [
+    '''\
+<p>Reke, ki se izlivajo neposredno v morje, lahko dobimo s poizvedbo:</p>
+<pre>
+?- river(River, _, _, Sea, _, _, _, _, _, _, _, _), Sea \= null.
+  River = 'Thjorsa', Sea = 'Atlantic Ocean' ;
+  River = 'Thames', Sea = 'North Sea' ;
+  …
+</pre>
+''',
+]
+
+hint = {}