Added recursion exercises.

24 files changed, 978 insertions, 2 deletions

diff --git a/python/problems/introduction/ballistics/sl.py b/python/problems/introduction/ballistics/sl.py
index b0f33e7..d4e03eb 100644
--- a/python/problems/introduction/ballistics/sl.py
+++ b/python/problems/introduction/ballistics/sl.py
@@ -15,7 +15,7 @@ bo letela krogla.</p>
 Poskusi, kako daleč gre pod kotom 45 in kako daleč pod 46 stopinj -- po 45 mora leteti dlje. 
 Preveri tudi kot 50 stopinj: če pod tem kotom leti nazaj (razdalja je negativna), 
 si ga gotovo nekje polomil.
-<p><i>Opomba: za pravilno delovanje moraš v programu najprej prebrati kot in potem hitrost.</i></p>
+<p><i>Opomba: za pravilno testiranje moraš v programu najprej prebrati kot in potem hitrost.</i></p>
 '''
 
 eval_expression = ['''\
@@ -56,7 +56,7 @@ hint = {
     'radians': ['''\
 <p>Poskusi <code>sin(30)</code>. Zakaj je rezultat negativen?</p>''',
                 '''\
-<p>Vse triginometrične funkcije sprejemajo kot v radianih in ne v stopinjah.</p>''', 
+<p>Vse triginometrične funkcije sprejemajo kot v radianih in ne v stopinjah.</p>''',
 ''' <p>V stopinjah ima cel krog 360°, v radianih pa \( 2 \\pi \). </p>''',
 ''' <p>Formula za pretvorbo med stopinjami in radiani je: </p>
 <pre>
diff --git a/python/problems/introduction/leap_year/common.py b/python/problems/introduction/leap_year/common.py
new file mode 100644
index 0000000..7dc7318
--- /dev/null
+++ b/python/problems/introduction/leap_year/common.py
@@ -0,0 +1,93 @@
+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
+import re
+
+id = 20107
+number = 7
+visible = True
+
+solution = '''\
+leto = int(input("Vnesi leto: "))
+if leto % 4 == 0 and (leto % 100 != 0 or leto % 400 == 0):
+    print("Je prestopno")
+else:
+    print("Ni prestopno")
+'''
+
+hint_type = {
+    'mod_expression': Hint('mod_expression'),
+    'printing': Hint('printing'),
+    'name_error': Hint('name_error'),
+    'unsupported_operand': Hint('unsupported_operand'),
+    'final_hint': Hint('final_hint'),
+}
+
+def test(python, code):
+    # List of inputs: (expression to eval, stdin).
+    test_in = [
+        (None, '1900\n'),
+        (None, '1950\n'),
+        (None, '2000\n'),
+        (None, '2016\n'),
+        (None, '2100\n'),
+    ]
+    test_out = [
+        "Ni prestopno",
+        "Ni prestopno",
+        "Je prestopno",
+        "Je prestopno",
+        "Ni prestopno"
+    ]
+
+    # List of outputs: (expression result, stdout, stderr, exception).
+    answers = python(code=code, inputs=test_in, timeout=1.0)
+    outputs = [ans[1] for ans in answers]
+
+    n_correct = 0
+    tin = None
+    for i, (output, correct) in enumerate(zip(outputs, test_out)):
+        if correct in output:
+            n_correct += 1
+        else:
+            tin = test_in[i][1]
+            tout = correct
+
+    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:
+        hints.append({'id': 'final_hint'})
+    return passed, hints
+
+def hint(python, code):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    test_in = [(None, '212\n')]
+    answer = python(code=code, inputs=test_in, timeout=1.0)
+    exc = answer[0][3]
+    exc_hint = get_exception_desc(answer[0][3])
+    if exc:
+        if 'NameError' in exc:
+            return [{'id':'name_error', 'args': {'message': exc}}]
+        elif 'not callable' in exc:
+            return [{'id':'not_callable', 'args': {'message': exc}}]
+        elif 'unsupported operand' in exc:
+            return [{'id':'unsupported_operand', 'args': {'message': exc}}]
+        elif 'TypeError' in exc:
+            return [{'id':'unsupported_operand', 'args': {'message': exc}}]
+        else:
+            return exc_hint
+
+    # if token % not in code, we have to teach them how to
+    # evaluate expressions.
+    if (not has_token_sequence(tokens, ['%'])):
+        return [{'id' : 'mod_expression'}]
+
+    # student is not using print function
+    if not has_token_sequence(tokens, ['print']):
+        return [{'id' : 'printing'}]
+
+    return None
diff --git a/python/problems/introduction/leap_year/en.py b/python/problems/introduction/leap_year/en.py
new file mode 100644
index 0000000..a2419f9
--- /dev/null
+++ b/python/problems/introduction/leap_year/en.py
@@ -0,0 +1,15 @@
+name = '*Leap year'
+
+description = '''\
+<p>Write a program that reads a number representing a year and determines whether
+this is a leap year. A leap year is divisible by 4, but not divisible by 100,
+except if it is divisible also by 400. Thence years 2004, 2008, and 2000 are
+leap years, while 2005 and 2100 are not.</p>'''
+
+hint = {
+    'plan': '''\
+<p>(translation missing)</p>''',
+
+    'no_input_call': '''\
+<p>(translation missing)</p>''',
+}
diff --git a/python/problems/introduction/leap_year/sl.py b/python/problems/introduction/leap_year/sl.py
new file mode 100644
index 0000000..236e761
--- /dev/null
+++ b/python/problems/introduction/leap_year/sl.py
@@ -0,0 +1,65 @@
+import server
+mod = server.problems.load_language('python', 'sl')
+
+name = '*Prestopno leto'
+
+description = '''\
+<p> Napiši program, ki preveri ali je leto prestopno. Leto je prestopno,
+ če je deljivo s 4, razen v primeru, ko je deljivo s 100,
+ takrat leto ni prestopno, razen takrat, ko je deljivo s 400,
+ takrat je leto prestopno. Tako so leta 2004, 2008 in 2000 prestopna,
+ leti 2005 in 2100 pa ne. </p>
+
+ <p> Če je leto prestopno, naj izpiše "Je prestopno", če ni, "Ni prestopno". '''
+
+printing = ['''\
+<p>V Pythonu izpisujemo s funkcijo <code>print</code>.</p>''',
+            '''\
+</p>Če želimo izpisati več elementov, jih ločimo z vejico.
+Imejmo spremenljivko <code>ime</code>, ki vsebuje naše ime, potem:
+<pre>
+print("Ime mi je", ime, ".")
+</pre>''']
+
+mod_expression = ['''\
+<p>Ostanek pri deljenju dobiš z operatorjem %.''']
+
+plan = ['''\
+<p>1. Preberi vrednost 2.izračunaj 3.izpiši.</p>''',
+        mod_expression,
+        printing
+
+]
+hint = {
+
+    'mod_expression': mod_expression,
+
+    'printing': printing,
+
+    'name_error' : [
+        mod.general_msg['error_head'],
+        mod.general_msg['general_exception'],
+        mod.general_msg['name_error'],
+        '''\
+<p>Verjetno uporabljaš spremenljivko, ki nima vrednosti. Ali v izrazu za
+izračun uporabljaš napačno spremenljivko? Ali pri izpisu morda poskušaš
+izpisati napačno spremenljivko?</p>'''
+    ],
+
+    'unsupported_operand' : [
+        mod.general_msg['error_head'],
+        mod.general_msg['general_exception'],
+        mod.general_msg['type_error'],
+        '''\
+<p>Verjetni razlog: funkcija <code>input</code> vrača vrednost tipa niz, ki jo
+moramo najprej pretvoriti v tip <code>int</code>, če želimo z njo
+računati:</p>
+<pre>
+v = int(input(" ...
+</pre>''',],
+
+    'final_hint' : [
+            '''\
+<p>Odlično, program deluje!<br>
+''']
+}
diff --git a/python/problems/recursion/common.py b/python/problems/recursion/common.py
new file mode 100644
index 0000000..f04b38b
--- /dev/null
+++ b/python/problems/recursion/common.py
@@ -0,0 +1,2 @@
+id = 2008
+number = 8
\ No newline at end of file
diff --git a/python/problems/recursion/depth_to/common.py b/python/problems/recursion/depth_to/common.py
new file mode 100644
index 0000000..3aad348
--- /dev/null
+++ b/python/problems/recursion/depth_to/common.py
@@ -0,0 +1,107 @@
+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 = 20804
+number = 4
+visible = True
+
+solution = '''\
+def depthto(fr, to):
+    if fr == to:
+        return 0
+    for c in children[fr]:
+        d = depthto(c, to)
+        if d is not None:
+            return d + 1
+'''
+
+precode = """
+children = {
+    "Adam": ["Matjaž", "Cilka", "Daniel", "Erik"],
+    "Aleksander": [],
+    "Alenka": [],
+    "Barbara": [],
+    "Cilka": [],
+    "Daniel": ["Elizabeta", "Hans"],
+    "Erik": [],
+    "Elizabeta": ["Ludvik", "Jurij", "Barbara", "Herman", "Mihael"],
+    "Franc": [],
+    "Herman": ["Margareta"],
+    "Hans": [],
+    "Jožef": ["Alenka", "Aleksander", "Petra"],
+    "Jurij": ["Franc", "Jožef"],
+    "Ludvik": [],
+    "Margareta": [],
+    "Matjaž": ["Viljem"],
+    "Mihael": [],
+    "Petra": [],
+    "Tadeja": [],
+    "Viljem": ["Tadeja"],
+}
+
+age = {
+    "Adam": 111, "Matjaž": 90, "Cilka": 88, "Daniel": 85, "Erik": 83,
+    "Viljem": 58, "Tadeja": 20, "Elizabeta": 67, "Hans": 64, "Ludvik": 50,
+    "Jurij": 49, "Barbara": 45, "Herman": 39, "Mihael": 32, "Franc": 30,
+    "Jožef": 29, "Margareta": 10, "Alenka": 5, "Aleksander": 7, "Petra": 9
+}"""
+
+hint_type = {
+    'final_hint': Hint('final_hint')
+}
+
+def test(python, code):
+    code = precode + "\n" + code
+    func_name = 'depthto'
+    tokens = get_tokens(code)
+    if not has_token_sequence(tokens, ['def', func_name]):
+        return False, [{'id' : 'no_func_name', 'args' : {'func_name' : func_name}}]
+
+    in_out = [
+        (('Hans', 'Hans'), 0),
+        (('Daniel', 'Hans'), 1),
+        (('Adam', 'Hans'), 2),
+        (('Adam', 'Franc'), 4),
+        (('Adam', 'Petra'), 5),
+        (('Elizabeta', 'Aleksander'), 3),
+        (('Adam', 'Tadeja'), 3),
+        (('Daniel', 'Ludvik'), 2)
+    ]
+
+    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=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:
+        hints.append({'id': 'final_hint'})
+
+    return passed, hints
+
+
+def hint(python, code):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    answer = python(code=code, inputs=[(None, None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    return None
diff --git a/python/problems/recursion/depth_to/en.py b/python/problems/recursion/depth_to/en.py
new file mode 100644
index 0000000..9cb993d
--- /dev/null
+++ b/python/problems/recursion/depth_to/en.py
@@ -0,0 +1,13 @@
+id = 20804
+name = 'Family tree: depth to'
+
+description = '''\
+<p>(translation missing)</p>'''
+
+hint = {
+    'plan': '''\
+<p>(translation missing)</p>''',
+
+    'no_input_call': '''\
+<p>(translation missing)</p>''',
+}
diff --git a/python/problems/recursion/depth_to/sl.py b/python/problems/recursion/depth_to/sl.py
new file mode 100644
index 0000000..e4315c0
--- /dev/null
+++ b/python/problems/recursion/depth_to/sl.py
@@ -0,0 +1,31 @@
+import server
+mod = server.problems.load_language('python', 'sl')
+
+id = 20804
+name = 'Družinsko drevo: globina do'
+
+description = '''\
+<p>
+Napišite funkcijo <code>depthto(fr, to)</code>, ki pove kako globoko v rodbini
+osebe <code>fr</code> je oseba z imenom <code>to</code>.
+Uporabite družinsko
+drevo (<a target="_blank" href="[%@resource novak.png%]">slika</a> in
+<a target="_blank" href="[%@resource slovar.html%]">slovar</a>). </p>
+<pre>
+>>> depthto('Daniel', 'Hans')
+1
+>>> depthto('Adam', 'Hans')
+2
+>>> depthto('Adam', 'Franc')
+4
+</pre>
+'''
+
+plan = []
+
+hint = {
+    'final_hint': ['''\
+<p>Program je pravilen! <br>
+</p>
+'''],
+}
diff --git a/python/problems/recursion/en.py b/python/problems/recursion/en.py
new file mode 100644
index 0000000..a1e8f91
--- /dev/null
+++ b/python/problems/recursion/en.py
@@ -0,0 +1,3 @@
+name = 'Recursion'
+description = ''
+
diff --git a/python/problems/recursion/family_tree_name/common.py b/python/problems/recursion/family_tree_name/common.py
new file mode 100644
index 0000000..d924665
--- /dev/null
+++ b/python/problems/recursion/family_tree_name/common.py
@@ -0,0 +1,103 @@
+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 = 20801
+number = 1
+visible = True
+
+solution = '''\
+def printnames(name):
+    print(name)
+    for c in children[name]:
+        printnames(c)
+'''
+
+hint_type = {
+    'final_hint': Hint('final_hint')
+}
+
+precode = """
+children = {
+    "Adam": ["Matjaž", "Cilka", "Daniel", "Erik"],
+    "Aleksander": [],
+    "Alenka": [],
+    "Barbara": [],
+    "Cilka": [],
+    "Daniel": ["Elizabeta", "Hans"],
+    "Erik": [],
+    "Elizabeta": ["Ludvik", "Jurij", "Barbara", "Herman", "Mihael"],
+    "Franc": [],
+    "Herman": ["Margareta"],
+    "Hans": [],
+    "Jožef": ["Alenka", "Aleksander", "Petra"],
+    "Jurij": ["Franc", "Jožef"],
+    "Ludvik": [],
+    "Margareta": [],
+    "Matjaž": ["Viljem"],
+    "Mihael": [],
+    "Petra": [],
+    "Tadeja": [],
+    "Viljem": ["Tadeja"],
+}
+
+age = {
+    "Adam": 111, "Matjaž": 90, "Cilka": 88, "Daniel": 85, "Erik": 83,
+    "Viljem": 58, "Tadeja": 20, "Elizabeta": 67, "Hans": 64, "Ludvik": 50,
+    "Jurij": 49, "Barbara": 45, "Herman": 39, "Mihael": 32, "Franc": 30,
+    "Jožef": 29, "Margareta": 10, "Alenka": 5, "Aleksander": 7, "Petra": 9
+}"""
+
+def test(python, code):
+    code = precode + "\n" + code
+
+    func_name = 'printnames'
+    tokens = get_tokens(code)
+    if not has_token_sequence(tokens, ['def', func_name]):
+        return False, [{'id' : 'no_func_name', 'args' : {'func_name' : func_name}}]
+
+    in_out = [
+        ('Hans', ['Hans']),
+        ('Herman', ['Herman', 'Margareta']),
+        ('Jurij', ['Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra']),
+        ('Viljem', ['Viljem', 'Tadeja']),
+        ('Daniel', ['Daniel', 'Elizabeta', 'Ludvik', 'Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra', 'Barbara', 'Herman', 'Margareta', 'Mihael', 'Hans']),
+        ('Adam', ['Adam', 'Matjaž', 'Viljem', 'Tadeja', 'Cilka', 'Daniel', 'Elizabeta', 'Ludvik', 'Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra', 'Barbara', 'Herman', 'Margareta', 'Mihael', 'Hans', 'Erik'])
+    ]
+
+    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=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[1].splitlines()
+        corr = len(res) == len(to) and set(res) == set(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:
+        hints.append({'id': 'final_hint'})
+
+    return passed, hints
+
+
+def hint(python, code):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    answer = python(code=code, inputs=[(None, None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    return None
diff --git a/python/problems/recursion/family_tree_name/en.py b/python/problems/recursion/family_tree_name/en.py
new file mode 100644
index 0000000..b5621df
--- /dev/null
+++ b/python/problems/recursion/family_tree_name/en.py
@@ -0,0 +1,13 @@
+id = 20801
+name = 'Family tree: printing names'
+
+description = '''\
+<p>(translation missing)</p>'''
+
+hint = {
+    'plan': '''\
+<p>(translation missing)</p>''',
+
+    'no_input_call': '''\
+<p>(translation missing)</p>''',
+}
diff --git a/python/problems/recursion/family_tree_name/sl.py b/python/problems/recursion/family_tree_name/sl.py
new file mode 100644
index 0000000..ff42c50
--- /dev/null
+++ b/python/problems/recursion/family_tree_name/sl.py
@@ -0,0 +1,42 @@
+import server
+mod = server.problems.load_language('python', 'sl')
+
+id = 20801
+name = 'Družinsko drevo: izpis imen'
+
+description = '''\
+<p>
+Napišite funkcijo <code>printnames(name)</code>, ki izpiše vsa imena v določeni rodbini.
+Uporabite družinsko
+drevo (<a target="_blank" href="[%@resource novak.png%]">slika</a> in
+<a target="_blank" href="[%@resource slovar.html%]">slovar</a>),
+ki ste ga spoznali na predavanjih. </p>
+<pre>
+>>> printnames('Hans')
+Hans
+>>> printnames('Daniel')
+Daniel
+Elizabeta
+Ludvik
+Jurij
+Franc
+Jožef
+Alenka
+Aleksander
+Petra
+Barbara
+Herman
+Margareta
+Mihael
+Hans
+</pre>
+'''
+
+plan = []
+
+hint = {
+    'final_hint': ['''\
+<p>Program je pravilen! <br>
+</p>
+'''],
+}
diff --git a/python/problems/recursion/family_tree_name_list/common.py b/python/problems/recursion/family_tree_name_list/common.py
new file mode 100644
index 0000000..880d8b1
--- /dev/null
+++ b/python/problems/recursion/family_tree_name_list/common.py
@@ -0,0 +1,104 @@
+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 = 20802
+number = 2
+visible = True
+
+solution = '''\
+def names(name):
+    xs = [name]
+    for c in children[ime]:
+        xs.extend(names(c))
+    return xs
+'''
+
+hint_type = {
+    'final_hint': Hint('final_hint')
+}
+
+precode = """
+children = {
+    "Adam": ["Matjaž", "Cilka", "Daniel", "Erik"],
+    "Aleksander": [],
+    "Alenka": [],
+    "Barbara": [],
+    "Cilka": [],
+    "Daniel": ["Elizabeta", "Hans"],
+    "Erik": [],
+    "Elizabeta": ["Ludvik", "Jurij", "Barbara", "Herman", "Mihael"],
+    "Franc": [],
+    "Herman": ["Margareta"],
+    "Hans": [],
+    "Jožef": ["Alenka", "Aleksander", "Petra"],
+    "Jurij": ["Franc", "Jožef"],
+    "Ludvik": [],
+    "Margareta": [],
+    "Matjaž": ["Viljem"],
+    "Mihael": [],
+    "Petra": [],
+    "Tadeja": [],
+    "Viljem": ["Tadeja"],
+}
+
+age = {
+    "Adam": 111, "Matjaž": 90, "Cilka": 88, "Daniel": 85, "Erik": 83,
+    "Viljem": 58, "Tadeja": 20, "Elizabeta": 67, "Hans": 64, "Ludvik": 50,
+    "Jurij": 49, "Barbara": 45, "Herman": 39, "Mihael": 32, "Franc": 30,
+    "Jožef": 29, "Margareta": 10, "Alenka": 5, "Aleksander": 7, "Petra": 9
+}"""
+
+def test(python, code):
+    code = precode + "\n" + code
+
+    func_name = 'names'
+    tokens = get_tokens(code)
+    if not has_token_sequence(tokens, ['def', func_name]):
+        return False, [{'id' : 'no_func_name', 'args' : {'func_name' : func_name}}]
+
+    in_out = [
+        ('Hans', ['Hans']),
+        ('Herman', ['Herman', 'Margareta']),
+        ('Jurij', ['Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra']),
+        ('Viljem', ['Viljem', 'Tadeja']),
+        ('Daniel', ['Daniel', 'Elizabeta', 'Ludvik', 'Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra', 'Barbara', 'Herman', 'Margareta', 'Mihael', 'Hans']),
+        ('Adam', ['Adam', 'Matjaž', 'Viljem', 'Tadeja', 'Cilka', 'Daniel', 'Elizabeta', 'Ludvik', 'Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra', 'Barbara', 'Herman', 'Margareta', 'Mihael', 'Hans', 'Erik'])
+    ]
+
+    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=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 = len(res) == len(to) and set(res) == set(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:
+        hints.append({'id': 'final_hint'})
+
+    return passed, hints
+
+
+def hint(python, code):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    answer = python(code=code, inputs=[(None, None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    return None
diff --git a/python/problems/recursion/family_tree_name_list/en.py b/python/problems/recursion/family_tree_name_list/en.py
new file mode 100644
index 0000000..9d1820a
--- /dev/null
+++ b/python/problems/recursion/family_tree_name_list/en.py
@@ -0,0 +1,13 @@
+id = 20802
+name = 'Family tree: list of names'
+
+description = '''\
+<p>(translation missing)</p>'''
+
+hint = {
+    'plan': '''\
+<p>(translation missing)</p>''',
+
+    'no_input_call': '''\
+<p>(translation missing)</p>''',
+}
diff --git a/python/problems/recursion/family_tree_name_list/sl.py b/python/problems/recursion/family_tree_name_list/sl.py
new file mode 100644
index 0000000..261e401
--- /dev/null
+++ b/python/problems/recursion/family_tree_name_list/sl.py
@@ -0,0 +1,28 @@
+import server
+mod = server.problems.load_language('python', 'sl')
+
+id = 20802
+name = 'Družinsko drevo: seznam imen'
+
+description = '''\
+<p>
+Podobno kot pri prejšnji nalogi napišite funkcijo <code>names(name)</code>, ki
+tokrat vrne vse imena v seznamu. Uporabite družinsko
+drevo (<a target="_blank" href="[%@resource novak.png%]">slika</a> in
+<a target="_blank" href="[%@resource slovar.html%]">slovar</a>). </p>
+<pre>
+>>> names('Hans')
+['Hans']
+>>> names('Daniel')
+['Daniel', 'Elizabeta', 'Ludvik', 'Jurij', 'Franc', 'Jožef', 'Alenka', 'Aleksander', 'Petra', 'Barbara', 'Herman', 'Margareta', 'Mihael', 'Hans']
+</pre>
+'''
+
+plan = []
+
+hint = {
+    'final_hint': ['''\
+<p>Program je pravilen! <br>
+</p>
+'''],
+}
diff --git a/python/problems/recursion/family_tree_youngest/common.py b/python/problems/recursion/family_tree_youngest/common.py
new file mode 100644
index 0000000..099c1d3
--- /dev/null
+++ b/python/problems/recursion/family_tree_youngest/common.py
@@ -0,0 +1,104 @@
+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 = 20803
+number = 3
+visible = True
+
+solution = '''\
+def youngest(name):
+    xs = [(age[name], name)]
+    for c in children[name]:
+        xs.append(youngest(c))
+    return min(xs)
+'''
+
+hint_type = {
+    'final_hint': Hint('final_hint')
+}
+
+precode = """
+children = {
+    "Adam": ["Matjaž", "Cilka", "Daniel", "Erik"],
+    "Aleksander": [],
+    "Alenka": [],
+    "Barbara": [],
+    "Cilka": [],
+    "Daniel": ["Elizabeta", "Hans"],
+    "Erik": [],
+    "Elizabeta": ["Ludvik", "Jurij", "Barbara", "Herman", "Mihael"],
+    "Franc": [],
+    "Herman": ["Margareta"],
+    "Hans": [],
+    "Jožef": ["Alenka", "Aleksander", "Petra"],
+    "Jurij": ["Franc", "Jožef"],
+    "Ludvik": [],
+    "Margareta": [],
+    "Matjaž": ["Viljem"],
+    "Mihael": [],
+    "Petra": [],
+    "Tadeja": [],
+    "Viljem": ["Tadeja"],
+}
+
+age = {
+    "Adam": 111, "Matjaž": 90, "Cilka": 88, "Daniel": 85, "Erik": 83,
+    "Viljem": 58, "Tadeja": 20, "Elizabeta": 67, "Hans": 64, "Ludvik": 50,
+    "Jurij": 49, "Barbara": 45, "Herman": 39, "Mihael": 32, "Franc": 30,
+    "Jožef": 29, "Margareta": 10, "Alenka": 5, "Aleksander": 7, "Petra": 9
+}"""
+
+def test(python, code):
+    code = precode + "\n" + code
+
+    func_name = 'youngest'
+    tokens = get_tokens(code)
+    if not has_token_sequence(tokens, ['def', func_name]):
+        return False, [{'id' : 'no_func_name', 'args' : {'func_name' : func_name}}]
+
+    in_out = [
+        ('Hans', (64, 'Hans')),
+        ('Daniel', (5, 'Alenka')),
+        ('Herman', (10, 'Margareta')),
+        ('Viljem', (20, 'Tadeja')),
+        ('Aleksander', (7, 'Aleksander')),
+        ('Adam', (5, 'Alenka'))
+    ]
+
+    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=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:
+        hints.append({'id': 'final_hint'})
+
+    return passed, hints
+
+
+def hint(python, code):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    answer = python(code=code, inputs=[(None, None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    return None
diff --git a/python/problems/recursion/family_tree_youngest/en.py b/python/problems/recursion/family_tree_youngest/en.py
new file mode 100644
index 0000000..ba3f813
--- /dev/null
+++ b/python/problems/recursion/family_tree_youngest/en.py
@@ -0,0 +1,13 @@
+id = 20803
+name = 'Family tree: the youngest'
+
+description = '''\
+<p>(translation missing)</p>'''
+
+hint = {
+    'plan': '''\
+<p>(translation missing)</p>''',
+
+    'no_input_call': '''\
+<p>(translation missing)</p>''',
+}
diff --git a/python/problems/recursion/family_tree_youngest/sl.py b/python/problems/recursion/family_tree_youngest/sl.py
new file mode 100644
index 0000000..04c2700
--- /dev/null
+++ b/python/problems/recursion/family_tree_youngest/sl.py
@@ -0,0 +1,29 @@
+import server
+mod = server.problems.load_language('python', 'sl')
+
+id = 20803
+name = 'Družinsko drevo: najmlajši'
+
+description = '''\
+<p>
+Funkcija <code>youngest(name)</code> naj vrne starost in ime
+najmlajšega člana določene rodbine.
+Uporabite družinsko
+drevo (<a target="_blank" href="[%@resource novak.png%]">slika</a> in
+<a target="_blank" href="[%@resource slovar.html%]">slovar</a>). </p>
+<pre>
+>>> youngest('Hans')
+(64, 'Hans')
+>>> youngest('Daniel')
+(5, 'Alenka')
+</pre>
+'''
+
+plan = []
+
+hint = {
+    'final_hint': ['''\
+<p>Program je pravilen! <br>
+</p>
+'''],
+}
diff --git a/python/problems/recursion/novak.png b/python/problems/recursion/novak.png
new file mode 100644
index 0000000..6bfc520
--- /dev/null
+++ b/python/problems/recursion/novak.png
diff --git a/python/problems/recursion/path_to/common.py b/python/problems/recursion/path_to/common.py
new file mode 100644
index 0000000..cf63b6c
--- /dev/null
+++ b/python/problems/recursion/path_to/common.py
@@ -0,0 +1,108 @@
+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 = 20805
+number = 5
+visible = True
+
+solution = '''\
+def pathto(fr, to):
+    if fr == to:
+        return [fr]
+    for c in children[fr]:
+        d = pathto(c, to)
+        if d is not None:
+            return [fr] + d
+'''
+
+hint_type = {
+    'final_hint': Hint('final_hint')
+}
+
+precode = """
+children = {
+    "Adam": ["Matjaž", "Cilka", "Daniel", "Erik"],
+    "Aleksander": [],
+    "Alenka": [],
+    "Barbara": [],
+    "Cilka": [],
+    "Daniel": ["Elizabeta", "Hans"],
+    "Erik": [],
+    "Elizabeta": ["Ludvik", "Jurij", "Barbara", "Herman", "Mihael"],
+    "Franc": [],
+    "Herman": ["Margareta"],
+    "Hans": [],
+    "Jožef": ["Alenka", "Aleksander", "Petra"],
+    "Jurij": ["Franc", "Jožef"],
+    "Ludvik": [],
+    "Margareta": [],
+    "Matjaž": ["Viljem"],
+    "Mihael": [],
+    "Petra": [],
+    "Tadeja": [],
+    "Viljem": ["Tadeja"],
+}
+
+age = {
+    "Adam": 111, "Matjaž": 90, "Cilka": 88, "Daniel": 85, "Erik": 83,
+    "Viljem": 58, "Tadeja": 20, "Elizabeta": 67, "Hans": 64, "Ludvik": 50,
+    "Jurij": 49, "Barbara": 45, "Herman": 39, "Mihael": 32, "Franc": 30,
+    "Jožef": 29, "Margareta": 10, "Alenka": 5, "Aleksander": 7, "Petra": 9
+}"""
+
+def test(python, code):
+    code = precode + "\n" + code
+
+    func_name = 'pathto'
+    tokens = get_tokens(code)
+    if not has_token_sequence(tokens, ['def', func_name]):
+        return False, [{'id' : 'no_func_name', 'args' : {'func_name' : func_name}}]
+
+    in_out = [
+        (('Hans', 'Hans'), ['Hans']),
+        (('Daniel', 'Hans'), ['Daniel', 'Hans']),
+        (('Adam', 'Hans'), ['Adam', 'Daniel', 'Hans']),
+        (('Adam', 'Franc'), ['Adam', 'Daniel', 'Elizabeta', 'Jurij', 'Franc']),
+        (('Adam', 'Petra'), ['Adam', 'Daniel', 'Elizabeta', 'Jurij', 'Jožef', 'Petra']),
+        (('Elizabeta', 'Aleksander'), ['Elizabeta', 'Jurij', 'Jožef', 'Aleksander']),
+        (('Adam', 'Tadeja'), ['Adam', 'Matjaž', 'Viljem', 'Tadeja']),
+        (('Daniel', 'Ludvik'), ['Daniel', 'Elizabeta', 'Ludvik'])
+    ]
+
+    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=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:
+        hints.append({'id': 'final_hint'})
+
+    return passed, hints
+
+
+def hint(python, code):
+    tokens = get_tokens(code)
+
+    # run one test first to see if there are any exceptions
+    answer = python(code=code, inputs=[(None, None)], timeout=1.0)
+    exc = get_exception_desc(answer[0][3])
+    if exc: return exc
+
+    return None
diff --git a/python/problems/recursion/path_to/en.py b/python/problems/recursion/path_to/en.py
new file mode 100644
index 0000000..703d818
--- /dev/null
+++ b/python/problems/recursion/path_to/en.py
@@ -0,0 +1,13 @@
+id = 20805
+name = 'Family tree: path to'
+
+description = '''\
+<p>(translation missing)</p>'''
+
+hint = {
+    'plan': '''\
+<p>(translation missing)</p>''',
+
+    'no_input_call': '''\
+<p>(translation missing)</p>''',
+}
diff --git a/python/problems/recursion/path_to/sl.py b/python/problems/recursion/path_to/sl.py
new file mode 100644
index 0000000..b53bd26
--- /dev/null
+++ b/python/problems/recursion/path_to/sl.py
@@ -0,0 +1,30 @@
+import server
+mod = server.problems.load_language('python', 'sl')
+
+id = 20805
+name = 'Družinsko drevo: pot do'
+
+description = '''\
+<p>
+Reši podobno nalogo kot je prejšnja, le da naj funkcija ne vrne razdalje do
+določene osebe, temveč pot do nje. Uporabite družinsko
+drevo (<a target="_blank" href="[%@resource novak.png%]">slika</a> in
+<a target="_blank" href="[%@resource slovar.html%]">slovar</a>). </p>
+<pre>
+>>> pathto('Daniel', 'Hans')
+['Daniel', 'Hans']
+>>> pathto('Adam', 'Hans')
+['Adam', 'Daniel', 'Hans']
+>>> pathto('Adam', 'Franc')
+['Adam', 'Daniel', 'Elizabeta', 'Jurij', 'Franc']
+</pre>
+'''
+
+plan = []
+
+hint = {
+    'final_hint': ['''\
+<p>Program je pravilen! <br>
+</p>
+'''],
+}
diff --git a/python/problems/recursion/sl.py b/python/problems/recursion/sl.py
new file mode 100644
index 0000000..be7d05a
--- /dev/null
+++ b/python/problems/recursion/sl.py
@@ -0,0 +1,3 @@
+name = 'Rekurzija'
+description = 'Vaje iz rekurzije'
+
diff --git a/python/problems/recursion/slovar.html b/python/problems/recursion/slovar.html
new file mode 100644
index 0000000..ed80a01
--- /dev/null
+++ b/python/problems/recursion/slovar.html
@@ -0,0 +1,44 @@
+<!DOCTYPE html>
+<html lang="sl">
+<head>
+  <meta charset="utf-8" />
+  <title></title>
+  <link rel="stylesheet" type="text/css" href="/css/codeq.css" />
+  <link rel="stylesheet" type="text/css" href="../../style.css" />
+</head>
+<body>
+
+<pre>
+children = {
+    "Adam": ["Matjaž", "Cilka", "Daniel", "Erik"],
+    "Aleksander": [],
+    "Alenka": [],
+    "Barbara": [],
+    "Cilka": [],
+    "Daniel": ["Elizabeta", "Hans"],
+    "Erik": [],
+    "Elizabeta": ["Ludvik", "Jurij", "Barbara", "Herman", "Mihael"],
+    "Franc": [],
+    "Herman": ["Margareta"],
+    "Hans": [],
+    "Jožef": ["Alenka", "Aleksander", "Petra"],
+    "Jurij": ["Franc", "Jožef"],
+    "Ludvik": [],
+    "Margareta": [],
+    "Matjaž": ["Viljem"],
+    "Mihael": [],
+    "Petra": [],
+    "Tadeja": [],
+    "Viljem": ["Tadeja"],
+}
+
+age = {
+    "Adam": 111, "Matjaž": 90, "Cilka": 88, "Daniel": 85, "Erik": 83,
+    "Viljem": 58, "Tadeja": 20, "Elizabeta": 67, "Hans": 64, "Ludvik": 50,
+    "Jurij": 49, "Barbara": 45, "Herman": 39, "Mihael": 32, "Franc": 30,
+    "Jožef": 29, "Margareta": 10, "Alenka": 5, "Aleksander": 7, "Petra": 9
+}
+</pre>
+
+</body>
+</html>