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:
null.Key to the solution here is to traverse two lists to get their lengths. Therefore, we can move the pointer for the longer list first and then compare elements of both lists.
1 /** 2 * Definition for singly-linked list. 3 * public class ListNode { 4 * int val; 5 * ListNode next; 6 * ListNode(int x) { 7 * val = x; 8 * next = null; 9 * } 10 * } 11 */ 12 public class Solution { 13 public ListNode getIntersectionNode(ListNode headA, ListNode headB) { 14 if (headA == null || headB == null) 15 return null; 16 ListNode p1 = headA, p2 = headB; 17 int l1 = 0, l2 = 0, ll = 0; 18 while (p1 != null) { 19 l1++; 20 p1 = p1.next; 21 } 22 while (p2 != null) { 23 l2++; 24 p2 = p2.next; 25 } 26 p1 = headA; 27 p2 = headB; 28 if (l2 >= l1) { 29 ll = l2 - l1; 30 while (ll > 0) { 31 p2 = p2.next; 32 ll--; 33 } 34 } else { 35 ll = l1 - l2; 36 while (ll > 0) { 37 p1 = p1.next; 38 ll--; 39 } 40 } 41 while (p1 != null && p2 != null) { 42 if (p1.val == p2.val) 43 return p1; 44 p1 = p1.next; 45 p2 = p2.next; 46 } 47 return null; 48 } 49 }
Intersection of Two Linked Lists 解答
原文：http://www.cnblogs.com/ireneyanglan/p/4812526.html