def create_linked_list(alist):
"""Given a Python list, create linked list in same order."""
if len(alist) == 0:
return None
first = Node(alist[0])
first.next = create_linked_list(alist[1:])
return first
def test_damaged_recursive_data_structures(self):
from ch06.expression import Expression, Value, add
from algs.node import Node
n = Node(3)
n.next = n # This is dangerous!
with self.assertRaises(RuntimeError):
print(sum_list(n))
a = Expression(add, Value(1), Value(5))
a.left = a # This is dangerous!
with self.assertRaises(RuntimeError):
print(a.eval())
def tournament_two_losers(A):
"""
Returns two largest values in A. Only works for lists whose length
is a power of 2. Each winner accumulates list of the values it beat,
from which you call max() to find the second largest.
"""
from algs.node import Node
if len(A) < 2:
raise ValueError('Must have at least two values')
if len(A) % 2 == 1:
raise ValueError('Only works for lists with even number of values.')
tourn = None
for i in range(0, len(A), 2):
tourn = Node(ExtendedMatch(A[i], A[i+1]), tourn)
while not tourn.next is None:
results = None
while tourn:
next_one = tourn.next.next
tv = tourn.value
tnv = tourn.next.value
if tv.larger > tnv.larger:
tv.add_loser(tnv.larger)
tourn.next = results # Keep tourn
results = tourn
else:
tnv.add_loser(tv.larger)
tourn.next.next = results # Keey tourn.next
results = tourn.next
tourn = next_one
tourn = results
# Find where second is hiding!
m = tourn.value
largest = m.larger
second = max(m.smaller)
return (largest,second)