LeetCode-Easy部分中标签为LinkedList 160. Intersection of Two Linked Lists

原题

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.

题目分析

求2个链表的交集所在的节点。注意题目中给出的注意事项。

代码实现

       public ListNode GetIntersectionNode(ListNode headA, ListNode headB)
        {
            if (headA == null || headB == null)
                return null;

            ListNode a = headA;
            ListNode b = headB;

            while (a!= b)
            {

                if (a == null)
                    a = headB;
                else
                {
                    a = a.next;
                }

                if (b == null)
                    b = headA;
                else
                {
                    b = b.next;
                }

            }
            return a;
        }

说实话这个代码不是非常好理解。我们做一个模拟看一下，到底这个算法的意思是什么。

        static void Main(string[] args)
        {
            SolutionLinkedList s = new SolutionLinkedList();
            ListNode headA = s.CreateLinkList(new int[] { 1, 2, 3，5,6 });
            ListNode headB = headA.next;
            ListNode interNode = s.GetIntersectionNode(headA, headB);

            Console.ReadLine();
        }

程序比较的过程

更多LinkList题目

http://blog.youkuaiyun.com/daigualu/article/details/69077428