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;
        }

        ListNode a = pHead1;
        ListNode b = pHead2;

        while (a != null || b != null) {
            if (a == b) {
                return a;
            }

            if (a == null) {
                a = pHead2;
            } else {
                a = a.next;
            }

            if (b == null) {
                b = pHead1;
            } else {
                b = b.next;
            }
        }

        return null;
    }
}