题解 | #两个链表的第一个公共结点#

import java.util.*;
/*
public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Solution {
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
        if(pHead1==null||pHead2==null){
            return null;
        }
        Stack<ListNode> stack1=new Stack<>();
        Stack<ListNode> stack2=new Stack<>();
        while(pHead1!=null){
            stack1.push(pHead1);
            pHead1=pHead1.next;
        }
        while(pHead2!=null){
            stack2.push(pHead2);
            pHead2=pHead2.next;
        }
        ListNode node1=stack1.pop();
        ListNode node2=stack2.pop();
        if(node1!=node2){
            return null;
        }
        while(!stack1.isEmpty()&&!stack2.isEmpty()){
            node1=stack1.pop();
            node2=stack2.pop();
            if(node1!=node2){
                return node1.next;
            }
        }
        return node1;
    }
}