leetcode 160.
Write a program to find the node at which the intersection of two singly linked lists begins.
For example, the following two linked lists:
A: a1 → a2
↘
c1 → c2 → c3
↗
B: b1 → b2 → b3
Solution. I got the cool but trick solution from here. O(n) time, O(1) space.
Define a and b Node to travel through 2 lists. The point is to let both a and b travel complete 2 lists.
a travels: a1 -> a2 -> c1 -> c2 -> c3 -> b1 -> b2 -> b3 -> c1
b travels: b1 -> b2 -> b3 -> c1 -> c2 -> c3 -> a1 -> a2 -> c1
If order to let a, b travel, below code is presented:
def getIntersectionNode(self, headA, headB):
a, b = headA, headB
while a != b:
a = a.next if a != None else headB
b = b.next if b != None else headA
return a
Check my code on github: link