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160. Intersection of Two Linked Lists

{leetcode}/problems/intersection-of-two-linked-lists/[LeetCode - Intersection of Two Linked Lists^]

Write a program to find the node at which the intersection of two singly linked lists begins.

For example, the following two linked lists:

{image_attr}

begin to intersect at node c1.

Example 1:

{image_attr} 
Input: intersectVal = 8, listA = [4,1,8,4,5], listB = [5,0,1,8,4,5], skipA = 2, skipB = 3
Output: Reference of the node with value = 8
Input Explanation: The intersected node's value is 8 (note that this must not be 0 if the two lists intersect). From the head of A, it reads as [4,1,8,4,5]. From the head of B, it reads as [5,0,1,8,4,5]. There are 2 nodes before the intersected node in A; There are 3 nodes before the intersected node in B.

Example 2:

{image_attr} 
Input: intersectVal = 2, listA = [0,9,1,2,4], listB = [3,2,4], skipA = 3, skipB = 1
Output: Reference of the node with value = 2
Input Explanation: The intersected node's value is 2 (note that this must not be 0 if the two lists intersect). From the head of A, it reads as [0,9,1,2,4]. From the head of B, it reads as [3,2,4]. There are 3 nodes before the intersected node in A; There are 1 node before the intersected node in B.

Example 3:

{image_attr} 
Input: intersectVal = 0, listA = [2,6,4], listB = [1,5], skipA = 3, skipB = 2
Output: null
Input Explanation: From the head of A, it reads as [2,6,4]. From the head of B, it reads as [1,5]. Since the two lists do not intersect, intersectVal must be 0, while skipA and skipB can be arbitrary values.
Explanation: The two lists do not intersect, so return null.

Notes:

  • If the two linked lists have no intersection at all, return null.

  • The linked lists must retain their original structure after the function returns.

  • You may assume there are no cycles anywhere in the entire linked structure.

  • Your code should preferably run in O(n) time and use only O(1) memory.

思路分析

没想到竟然可以将两个链表"相加"就可以得出正确结果：两个"相加"，正好两个长度相等，最后部分就是重叠部分，双指针完美搞定！

一刷
link:{sourcedir}/_0160_IntersectionOfTwoLinkedLists.java[role=include]
二刷
link:{sourcedir}/_0160_IntersectionOfTwoLinkedLists_2.java[role=include]
三刷
link:{sourcedir}/_0160_IntersectionOfTwoLinkedLists_3.java[role=include]