两相交链表

/**
 * 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) {
        //思路：走完A走B 走完B走A 当两个链表指向相同元素的时候
        //就是相交的节点. 否则就指向空
        ListNode h1 = headA;
        ListNode h2 = headB;
        
        while(h1 != h2){
            h1 = h1 ==null ? headB : h1.next ; 
            h2 = h2 == null ? headA : h2.next;
        }
        return h1;
    }
}