LeetCode 86. Partition List（链表分区）

最新推荐文章于 2024-05-23 17:19:40 发布

jmspan

最新推荐文章于 2024-05-23 17:19:40 发布

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分类专栏：链表排序分区筛选文章标签： leetcode

本文链接：https://blog.youkuaiyun.com/jmspan/article/details/51473511

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本文介绍了一种链表分区算法的实现方式，该算法能够确保所有小于给定值x的节点出现在大于等于x的节点之前，并保持各分区内部节点原有的相对顺序。通过使用两个辅助链表来分别收集小于x和不小于x的节点，最后将两部分链接起来返回结果。

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原题网址：https://leetcode.com/problems/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.

方法：用不同的变量存储不同的区。

/**
 * 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) {
        ListNode less = new ListNode(0);
        ListNode tail = less;
        ListNode current = head;
        ListNode notLess = new ListNode(0);
        ListNode notLessTail = notLess;
        while (current != null) {
            if (current.val < x) {
                tail.next = current;
                current = current.next;
                tail = tail.next;
                tail.next = null;
            } else {
                notLessTail.next = current;
                current = current.next;
                notLessTail = notLessTail.next;
                notLessTail.next = null;
            }
        }
        if (less.next != null) {
            tail.next = notLess.next;
            return less.next;
        }
        return notLess.next;
    }
}