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.
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scratch/facebook/intersecting-linked-lists.py
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34
scratch/facebook/intersecting-linked-lists.py
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class LinkedList(object):
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def __init__(self, x):
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self.val = x
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self.next = None
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def __repr__(self):
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if self.next:
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return "{} -> {}".format(self.val, self.next)
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return "{}".format(self.val)
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def find_intersection(a, b):
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init_a, init_b = a, b
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while a != b:
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a = a.next if a.next else init_b
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b = b.next if b.next else init_a
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return a
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# make A...
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e1 = LinkedList(5)
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d1 = LinkedList(2); d1.next = e1
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c1 = LinkedList(3); c1.next = d1 # shared
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b1 = LinkedList(1); b1.next = c1 # shared
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a1 = LinkedList(4); a1.next = b1 # shared
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# make B...
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c2 = LinkedList(1); c2.next = c1
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b2 = LinkedList(5); b2.next = c2
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a2 = LinkedList(6); a2.next = b2
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print(a1)
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print(a2)
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print(find_intersection(a1, a2).val)
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