[LeetCode-interview algorithm classic-Java implementation] [092-Reverse Linked List II (Reverse Single-Chain List II)], leetcode -- java

[LeetCode-interview algorithm classic-Java implementation] [092-Reverse Linked List II (Reverse Single-Chain List II)], leetcode -- java
[092-Reverse Linked List II (Reverse single-chain table II )][LeetCode-interview algorithm classic-Java implementation] [directory indexes for all questions]Original question

Reverse a linked list from position m to n. Do it in-place and in one-pass.
For example:
Given1->2->3->4->5->NULL,m = 2Andn = 4,
Return1->4->3->2->5->NULL.
　　Note:
Given m, n satisfy the following condition:
　　1 ≤ m ≤ n ≤ lengthOf list.

Theme

Given a single-chain table, convert the elements between m and n.
The given n and m are valid and are solved using the in-situ method (using constant auxiliary space)

Solutions

First, find the prev of the first element to be reversed, then calculate the number of elements to be reversed, insert the element into the header, insert it behind the prev, and keep the linked list continuously open.

Code Implementation

Linked List Node Type

public class ListNode {    int val;    ListNode next;    ListNode(int x) { val = x; }}

Algorithm Implementation class

Public class Solution {public ListNode reverseBetween (ListNode head, int m, int n) {ListNode root = new ListNode (0); ListNode p = root; root. next = head; for (int I = 1; I <m & p! = Null; I ++) {p = p. next;} if (p! = Null) {ListNode q = p. next; ListNode r; // if m is a negative number, it is considered to be switching from the first one if (m <1) {m = 1;} n = n-m + 1; // n indicates the number of nodes to be changed. // use the end insertion method only when there are two nodes. The number of end inserts is n-1 for (int I = 1; I <n & q. next! = Null; I ++) {// is the node r = q. next; // perform the end insertion Operation after the q node. next = r. next; r. next = p. next; p. next = r;} head = root. next;} return head ;}}

Evaluation Result

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Note Please refer to the following link for more information: http://blog.csdn.net/derrantcm/article/details/47310547]

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