LeetCode Intersection of Two Linked Lists solution report, leetcode

LeetCode Intersection of Two Linked Lists solution report, leetcode
Https://oj.leetcode.com/problems/intersection-of-two-linked-lists/
Calculate the first public node of the two linked lists. If there is no public node, null is returned.

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

Solution:
1) if the last node of the two linked lists is the same, the two linked lists must have an intersection.
2) Calculate the length of the two linked lists respectively, and then move the linked list with the length forward: LengA-LengB, align the two linked lists, and traverse them together until the first same node is found.

public class Solution {        public ListNode getIntersectionNode(ListNode headA, ListNode headB) {        if(headA==null||headB==null) {            return null;        }        int lengthA = 1;        int lengthB = 1;                ListNode iterA = headA;        while(iterA.next!=null) {            iterA = iterA.next;            lengthA++;        }                ListNode iterB = headB;        while(iterB.next!=null) {            iterB = iterB.next;            lengthB++;        }                if(iterA!=iterB) {            return null;        }                if(lengthA>lengthB) {            int tmp = lengthA - lengthB;            while(tmp>0) {                headA = headA.next;                tmp--;            }        } else {            int tmp = lengthB - lengthA;            while(tmp>0) {                headB = headB.next;                tmp--;            }        }                                        while(headA!=headB) {            headA = headA.next;            headB = headB.next;        }                return headA;    }}