[编程打卡]两个链表的第一个公共节点(Java实现)

[编程打卡]两个链表的第一个公共节点(Java实现) 题目来源

剑指offer第36题
https://www.nowcoder.com/practice/6ab1d9a29e88450685099d45c9e31e46?tpId=13tqId=11189tPage=2rp=2ru=/ta/coding-interviewsqru=/ta/coding-interviews/question-ranking

题目描述

输入两个链表,找出它们的第一个公共结点。

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

    ListNode(int val) {
        this.val = val;
    }
}*/
import java.util.*;
public class Solution {
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
         SetListNodeset=new HashSet();
        while(pHead1!=null){
            set.add(pHead1);
            pHead1=pHead1.next;
        }
         while(pHead2!=null){
            if(set.contains(pHead2))
                return pHead2;
            pHead2=pHead2.next;
        }
        return pHead2;
    }
}
/*
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 d=null;
        int i=0;
        ListNode l1=pHead1;
        ListNode l2=pHead2;
        int count1=countlength(pHead1);
        int count2=countlength(pHead2);
        int x;
        if(count1count2){
            x=count2-count1;
             while(x--0){
                  pHead2=pHead2.next;
             }
        }else
        {
            x=count1-count2;
            while(x--0){
                  pHead1=pHead1.next;
             }
        }
        while(pHead1!=nullpHead2!=null){
             if(pHead1==pHead2)
                      return pHead1;
                  pHead1=pHead1.next;
                  pHead2=pHead2.next;
                  
              }
        return d;
    }
    int countlength(ListNode pHead1){
        int count1=0;
        while(pHead1!=null){
            pHead1=pHead1.next;
            count1++;
        }
        return count1;
    }
}
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