160. Intersection of Two Linked Lists #

题目 #

给定两个单链表的头节点headA和headB，找出并返回两个单链表相交的起始节点。如果两个链表不存在相交节点，返回null。

思路 #

代码 #

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 ptrA = headA, ptrB = headB;
        while (ptrA != ptrB) {
            ptrA = ptrA.next;
            ptrB = ptrB.next;
            if (ptrA == null && ptrB == null) return null;
            else if (ptrA == null) ptrA = headB;
            else if (ptrB == null) ptrB = headA;
        }
        return ptrA;
    }
}