题目
给定一个单链表和数值x，划分链表使得所有小于x的节点排在大于等于x的节点之前。
你应该保留两部分内链表节点原有的相对顺序。
样例
给定链表 1->4->3->2->5->2->null，并且 x=3
返回** 1->2->2->4->3->5->null**
代码
/**
* Definition for ListNode.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int val) {
* this.val = val;
* this.next = null;
* }
* }
*/
public class Solution {
/**
* @param head: The first node of linked list.
* @param x: an integer
* @return: a ListNode
*/
public ListNode partition(ListNode head, int x) {
// write your code here
if(head == null) return null;
ListNode leftDummy = new ListNode(0);
ListNode rightDummy = new ListNode(0);
ListNode left = leftDummy, right = rightDummy;
while (head != null) {
if (head.val < x) {
left.next = head;
left = head;
} else {
right.next = head;
right = head;
}
head = head.next;
}
right.next = null;
left.next = rightDummy.next;
return leftDummy.next;
}
}
