1 files changed, 114 insertions, 0 deletions
diff --git a/python/problems/functions/greatest_negative/common.py b/python/problems/functions/greatest_negative/common.py
new file mode 100644
index 0000000..01dfce3
--- /dev/null
+++ b/python/problems/functions/greatest_negative/common.py
@@ -0,0 +1,114 @@
+# coding=utf-8
+
+import re
+from python.util import has_token_sequence, string_almost_equal, \
+    string_contains_number, get_tokens, get_numbers, get_exception_desc
+from server.hints import Hint, HintSequence
+
+id = 197
+group = 'functions'
+number = 3
+visible = True
+
+solution = '''\
+def max_neg(xs):
+    mn = None
+    for x in xs:
+        if x < 0 and (mn == None or x > mn):
+            mn = x
+    return mn
+'''
+
+hint_type = {
+    'no_def': Hint('no_def'),
+    'no_return': Hint('no_return'),
+    'return_indent': Hint('return_indent'),
+    'for_loop': Hint('for_loop'),
+    'not_int': Hint('not_int'),
+    'return_first': Hint('return_first'),
+    'return_last': Hint('return_last'),
+    'return_greatest': Hint('return_greatest'),
+    'return_positive': Hint('return_positive'),
+    'return_absolute': Hint('return_absolute'),
+}
+
+
+def test(python, code):
+    test_lists = [[6, 4, 2, 0],
+               [4, 6, 2, -1],
+               [4, -2, -6, 0],
+               [4, 2, 0, 6],
+               [6, -8, 2, 0],
+               [-8, 6, 2, 0],
+               [8, -6, -2, 0],
+               [-5, -6, -2, -1],
+               [-8, 0, -6, -2],
+               [-1, -8, -6, -2],
+               [42],
+               [-42]]
+
+    test_in = [('max_neg(%s)'%str(l), None) for l in test_lists]
+    test_out = [None, -1, -2, None, -8, -8, -2, -1, -2, -1, None, -42]
+
+    answers = python(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)):
+        n_correct += ans[0] == to
+        if ans[0] != to:
+            tin = test_lists[i]
+            tout = to
+    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)}})
+
+    return n_correct == len(test_in), hints
+
+def hint(python, code):
+    tokens = get_tokens(code)
+    # having function max_neg is necessary!
+    if not has_token_sequence(tokens, ['max_neg']):
+        return [{'id' : 'no_func_name', 'args' : {'func_name' : 'max_neg'}}]
+
+    # run one test to see if there are any exceptions
+    answer = python(code=code, inputs=[('max_neg([1, 3, -3, -6, 4, 3, 2])', None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    # if has no def, tell him to define the function
+    if not has_token_sequence(tokens, ['def']):
+        return [{'id' : 'no_def'}]
+
+    # if has no return, tell him to return the value
+    if not has_token_sequence(tokens, ['return']):
+        return [{'id' : 'no_return'}]
+
+    # if has no loop, tell him to use it
+    if not has_token_sequence(tokens, ['while']) and \
+       not has_token_sequence(tokens, ['for']):
+        return [{'id' : 'for_loop'}]
+
+    # if has no condition if, tell him to use it
+    if not has_token_sequence(tokens, ['if']):
+        return [{'id' : 'if_clause'}]
+
+    # test for wrong answers
+    res = answer[0][0]
+    if not isinstance(res, int):
+        return [{'id' : 'not_int'}]
+    cases = {
+        1: [{'id' : 'return_first'}],
+        2: [{'id' : 'return_last'}],
+        4: [{'id' : 'return_greatest'}],
+        3: [{'id' : 'return_positive'}],
+        -6: [{'id' : 'return_absolute'}]
+    }
+    if res in cases:
+        return cases[res]
+
+    # if has no return at the beginning of block,
+    # tell not to return from for
+    if not has_token_sequence(tokens, ['\n', 'return']):
+        return [{'id' : 'return_indent'}]
+
+    return None