题解 |# BM10 两个链表的第一个公共结点#

/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
import java.util.HashSet;
public class Solution {
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
        HashSet<ListNode> hashList=new HashSet<ListNode>();
        
            
        while(pHead1!=null || pHead2!=null){
            if(hashList.contains(pHead1) ){
                    return pHead1;
            }
            if(pHead1!=null){
                hashList.add(pHead1);
                pHead1=pHead1.next;
            }
              
            if(hashList.contains(pHead2)){
                return pHead2;
            }
            
            if(pHead2!=null){
                hashList.add(pHead2);
                pHead2=pHead2.next;
            }      

        }
        
        return null;
    }
}