def test_normal(): lst = [1, 2, 3, 4, 5] link = list2link(lst) assert find_kth_from_tail(link, 3).val == 3
def test_k0(): lst = [1, 2, 3, 4, 5] link = list2link(lst) assert find_kth_from_tail(link, 0).val == None
def test_none(): lst = [] link = list2link(lst) assert find_kth_from_tail(link, 1).val == None
def test_kbiger_than_len(): lst = [1, 2, 3, 4, 5] link = list2link(lst) assert find_kth_from_tail(link, 6).val == None
def test_head(): lst = [1, 2, 3, 4, 5] link = list2link(lst) assert find_kth_from_tail(link, 5).val == 1