1 files changed, 75 insertions, 0 deletions
diff --git a/python/problems/recursion/factorial/common.py b/python/problems/recursion/factorial/common.py
new file mode 100644
index 0000000..fec787b
--- /dev/null
+++ b/python/problems/recursion/factorial/common.py
@@ -0,0 +1,75 @@
+import re
+from python.util import has_token_sequence, string_almost_equal, \
+    string_contains_number, get_tokens, get_numbers, get_exception_desc, \
+    all_tokens, has_comprehension, has_loop, almost_equal, get_ast
+from server.hints import Hint
+
+id = 20806
+number = 6
+visible = True
+
+solution = '''\
+def factorial(n):
+    if n == 0:
+        return 1
+    return n * factorial(n - 1)
+'''
+
+hint_type = {
+    'final_hint': Hint('final_hint'),
+    'has_loop': Hint('has_loop')
+}
+
+def test(python, code, aux_code=''):
+    func_name = 'factorial'
+    tokens = get_tokens(code)
+    ast = get_ast(code)
+    if not has_token_sequence(tokens, ['def', func_name]):
+        return False, [{'id' : 'no_func_name', 'args' : {'func_name' : func_name}}]
+
+    in_out = [
+        (0, 1),
+        (1, 1),
+        (2, 2),
+        (12, 479001600),
+        (20, 2432902008176640000)
+    ]
+
+    test_in = [('{0}({1})'.format(func_name, str(l[0])), None)
+               for l in in_out]
+    test_out = [l[1] for l in in_out]
+
+    answers = python(code=aux_code+code, inputs=test_in, timeout=1.0)
+    n_correct = 0
+    tin, tout = None, None
+    for i, (ans, to) in enumerate(zip(answers, test_out)):
+        res = ans[0]
+        corr = res == to
+        n_correct += corr
+        if not corr:
+            tin = test_in[i][0]
+            tout = to
+
+    passed = n_correct == len(test_in)
+    hints = [{'id': 'test_results', 'args': {'passed': n_correct, 'total': len(test_in)}}]
+    if tin:
+        hints.append({'id': 'problematic_test_case', 'args': {'testin': str(tin), 'testout': str(tout)}})
+    if passed:
+        if has_loop(ast):
+            hints.append({'id': 'has_loop'})
+        else:
+            hints.append({'id': 'final_hint'})
+
+
+    return passed, hints
+
+
+def hint(python, code, aux_code=''):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    answer = python(code=aux_code+code, inputs=[(None, None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    return None