LeetCode：148. Sort List（对链表进行排序）

快来打我* 2022-04-11 11:41 71阅读 0赞

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**相关文章：**

1.  **[LeetCode：55. Jump Game（跳远比赛）][LeetCode_55. Jump Game]**
2.  **[Leetcode：300. Longest Increasing Subsequence（最大增长序列）][Leetcode_300. Longest Increasing Subsequence]**
3.  **[LeetCode：560. Subarray Sum Equals K（找出数组中连续子串和等于k）][LeetCode_560. Subarray Sum Equals K_k]**

--------------------

### 题目描述： ###

Sort a linked list in *O*(*n* log *n*) time using constant space complexity.

**Example 1:**

Input: 4->2->1->3
    Output: 1->2->3->4

**Example 2:**

Input: -1->5->3->4->0
    Output: -1->0->3->4->5

--------------------

### java实现方法1： ###

/**
         * 对链表进行排序
         *
         * @param head 节点head
         * @return listNode节点
         */
        public ListNode sortList(ListNode head) {
            if (head == null || head.next == null) {
                return head;
            }
            ListNode lastNode = getLastNode(head);
            return merge(sortList(head), sortList(lastNode));
        }
    
        /**
         * 获取下半部分节点
         *
         * @param node 节点
         * @return 后部分节点
         */
        private ListNode getLastNode(ListNode node) {
            ListNode fast = node;
            ListNode slow = node;
            ListNode breakN = node;
            while (fast != null && fast.next != null) {
                fast = fast.next.next;
                breakN = slow;
                slow = slow.next;
            }
            breakN.next = null;
            return slow;
        }
        /**
         * 合并两个链表
         *
         * @param l1 链表l1
         * @param l2 链表l2
         * @return 合并后链表
         */
        private ListNode merge(ListNode l1, ListNode l2) {
            if (l1 == null) {
                return l2;
            }
            if (l2 == null) {
                return l1;
            }
            if (l1.val <= l2.val) {
                l1.next = merge(l1.next, l2);
                return l1;
            } else {
                l2.next = merge(l1, l2.next);
                return l2;
            }
        }

时间复杂度：O(n.logn)

空间复杂度：O(1)

--------------------

### Python实现方法1： ###

def sort_list(self, head: ListNode) -> ListNode:
            '''
                对链表进行排序
            Args:
                head: 节点
            Returns:
                链表
            '''
            if not head or not head.next:
                return head
            last_node = self.get_last_node(head)
            l1 = self.sort_list(head)
            l2 = self.sort_list(last_node)
            return self.merge(l1, l2)
    
        def get_last_node(self, node: ListNode) -> ListNode:
            '''
                获取后部分节点
            Args:
                node: node节点
            Returns:
                最后部分节点
            '''
            fast = node
            slow = node
            break_node = node
            while fast and fast.next:
                fast = fast.next.next
                break_node = slow
                slow = slow.next
            break_node.next = None
            return slow
    
        def merge(self, l1: ListNode, l2: ListNode) -> ListNode:
            '''
                合并两个节点
            Args:
                l1: l1链表
                l2: l2链表
            Returns:
                合并的链表
            '''
            if not l1:
                return l2
            if not l2:
                return l1
            if l1.val <= l2.val:
                l1.next = self.merge(l1.next, l2)
                return l1
            else:
                l2.next = self.merge(l1, l2.next)
                return l2

时间复杂度：O(n.logn)

空间复杂度：O(1)

--------------------

### 源码地址： ###

[https://github.com/zhangyu345293721/leetcode][https_github.com_zhangyu345293721_leetcode]

[github]: https://github.com/zhangyu345293721
[LeetCode_55. Jump Game]: https://blog.csdn.net/zy345293721/article/details/84991870
[Leetcode_300. Longest Increasing Subsequence]: https://blog.csdn.net/zy345293721/article/details/84984249
[LeetCode_560. Subarray Sum Equals K_k]: https://blog.csdn.net/zy345293721/article/details/84952201
[https_github.com_zhangyu345293721_leetcode]: https://github.com/zhangyu345293721/leetcode