21.1.3 leetcode86

题目链接：https://leetcode-cn.com/problems/partition-list/

题意：在保证原有顺序的情况下，把链表中比x小的排前面，比x大的排后面。

分析：链表排序https://www.cnblogs.com/qingjiuling/p/14017450.html的简化版

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode partition(ListNode head, int x) {
        ListNode small = new ListNode(0);
        ListNode smallHead = small;
        ListNode large = new ListNode(0);
        ListNode largeHead = large;
        while(head!=null){
            if(head.val<x){
                small.next=head;
                small=small.next;
            }
            else{
                large.next=head;
                large=large.next;
            }
            head=head.next;
        }
        large.next=null;
        small.next=largeHead.next;
        return smallHead.next;
    }
}