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:

A:          a1 → a2                   ↘                     c1 → c2 → c3                   ↗            B:     b1 → b2 → b3

begin to intersect at node c1.

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.

题目意思：给定两个链表，找到他们的第一个公共节点；

解题思路：先确定两个链表节点个数的差，然后让两个指针间隔节点差同步向前，当遇到两个节点的val相等时为第一个公共节点；

代码如下：