两个链表的第一个公共结点

题目描述
输入两个链表，找出它们的第一个公共结点。

import java.util.Stack;

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