86. Partition List

题目86. Partition List

Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.
You should preserve the original relative order of the nodes in each of the two partitions.
For example,
Given 1->4->3->2->5->2 and x = 3,
return 1->2->2->4->3->5.

public class Solution {
    public ListNode partition(ListNode head, int x) {
        if(head == null || head.next == null){
            return head;
        }
        
        ListNode lessHead = new ListNode(1);
        ListNode lessTail = lessHead;
        ListNode moreHead = new ListNode(1);
        ListNode moreTail = moreHead;
        
        ListNode node = head;
        ListNode tempNode = null;
        while(node != null){
            tempNode = node.next;
            if(node.val < x){
                lessTail.next = node;
                lessTail = lessTail.next;
            }else{
                moreTail.next = node;
                moreTail = moreTail.next;
            }
            node = tempNode;
        }
        
        lessTail.next = moreHead.next;
        moreTail.next = null;
        return lessHead.next;
    }
}