题解 | #牛群分隔#

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @param x int整型 
     * @return ListNode类
     */
    public ListNode cow_partition (ListNode head, int x) {
        // write code here
        ListNode lt = new ListNode(-1);
        ListNode gt = new ListNode(-1);
        ListNode curLt = lt;
        ListNode curGt = gt;
        while(head != null){
            if(head.val < x){
                curLt.next = new ListNode(head.val);
                curLt = curLt.next;
                head = head.next;
            }else{
                curGt.next = new ListNode(head.val);
                curGt = curGt.next;
                head = head.next;
            }
        }
        curLt.next = gt.next;
        return lt.next;
    }
}