【LeetCode】160.Intersection of Two Linked Lists(Easy)解题报告

【LeetCode】160.Intersection of Two Linked Lists(Easy)解题报告

题目地址：https://leetcode.com/problems/intersection-of-two-linked-lists/description/

题目描述：

  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.

  整个过程找到两个链表相交的点，两链表长度可能不同，但是分别循环之后必定同时到达交点。

Solution:

/**
* Definition for singly-linked list.
* public class ListNode {
*     int val;
*     ListNode next;
*     ListNode(int x) {
*         val = x;
*         next = null;
*     }
* }
*/
public class Solution {
public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
if(headA == null || headB == null){
return null;
}
ListNode a = headA;
ListNode b = headB;
while(a!=b){
a= a==null ? headB : a.next;
b= b==null ? headA : b.next;
}
return a;
}
}

Date：2017年11月15日