Partition List

给一个链表, 和一个值x. 以x为pivot做partition.

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