Find the intersection (if any) between two linked lists

As with most linked list questions, this one involves an arcane trick from the
neck-bearded playbook.
This commit is contained in:
William Carroll 2020-11-15 17:42:44 +00:00
parent c8330adfcb
commit 363519273a

View file

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class LinkedList(object):
def __init__(self, x):
self.val = x
self.next = None
def __repr__(self):
if self.next:
return "{} -> {}".format(self.val, self.next)
return "{}".format(self.val)
def find_intersection(a, b):
init_a, init_b = a, b
while a != b:
a = a.next if a.next else init_b
b = b.next if b.next else init_a
return a
# make A...
e1 = LinkedList(5)
d1 = LinkedList(2); d1.next = e1
c1 = LinkedList(3); c1.next = d1 # shared
b1 = LinkedList(1); b1.next = c1 # shared
a1 = LinkedList(4); a1.next = b1 # shared
# make B...
c2 = LinkedList(1); c2.next = c1
b2 = LinkedList(5); b2.next = c2
a2 = LinkedList(6); a2.next = b2
print(a1)
print(a2)
print(find_intersection(a1, a2).val)