8.链表分割

import java.util.*;

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

    ListNode(int val) {
        this.val = val;
    }
}*/
public class Partition {
    public ListNode partition(ListNode pHead, int x) {
        // write code here
        Queue<ListNode>q1=new LinkedList<>();
        Queue<ListNode>q2=new LinkedList<>();
        while(pHead!=null){
            if(pHead.val<x)
                q1.offer(pHead);
            else{
                q2.offer(pHead);
            }
            pHead=pHead.next;
        }
        ListNode tmp=null;
        if(!q1.isEmpty()){
            pHead=q1.poll();
        }else if(!q2.isEmpty()){
            pHead=q2.poll();
        }
        tmp=pHead;
        while(!q1.isEmpty()){
            tmp.next=q1.poll();
            tmp=tmp.next;
        }
        while(!q2.isEmpty()){
            tmp.next=q2.poll();
            tmp=tmp.next;
        }
        tmp.next=null;
        return pHead;
        
    }
}