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) {
        ListNode ph1 = pHead1;
        ListNode ph2 = pHead2;
        int l1 = 0;
        int l2 = 0;
        while(ph1 != null){
            ph1 = ph1.next;
            l1++;
        }
        while(ph2 != null){
            ph2 = ph2.next;
            l2++;
        }
        if(l1 == l2){
            while(pHead1 != pHead2){
                pHead1 = pHead1.next;
                pHead2 = pHead2.next;
            }
            return pHead1;
        }
        else if(l1>l2){
            int l= l1-l2;
            while(l-->0){
                pHead1 = pHead1.next;
            }
            while(pHead1 != pHead2){
                pHead1 = pHead1.next;
                pHead2 = pHead2.next;
            }
            return pHead1;
        }
        else{
            int l= l2-l1;
            while(l-->0){
                pHead2 = pHead2.next;
            }
            while(pHead1 != pHead2){
                pHead1 = pHead1.next;
                pHead2 = pHead2.next;
            }
            return pHead1;
        }
    }
}

常规思路求解，得出长度差然后先走长度差个节点 之后就一起走