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ReverseLinkedList_II.js
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// Source : https://leetcode.com/problems/reverse-linked-list-ii
// Author : Dean Shi
// Date : 2017-03-27
/***************************************************************************************
*
* Reverse a linked list from position m to n. Do it in-place and in one-pass.
*
* For example:
* Given 1->2->3->4->5->NULL, m = 2 and n = 4,
*
* return 1->4->3->2->5->NULL.
*
* Note:
* Given m, n satisfy the following condition:
* 1 ≤ m ≤ n ≤ length of list.
*
*
***************************************************************************************/
/**
* Definition for singly-linked list.
* function ListNode(val) {
* this.val = val;
* this.next = null;
* }
*/
/**
* @param {ListNode} head
* @param {number} m
* @param {number} n
* @return {ListNode}
*/
var reverseBetween = function(head, m, n) {
if (m === 1) {
return reverse(head, n - 1)[0]
}
head.next = reverseBetween(head.next, m - 1, n - 1)
return head
};
function reverse(head, n) {
if (!n) return [head, head.next]
const [node, nodeNext] = reverse(head.next, n - 1)
const next = head.next
next.next = head
head.next = nodeNext
return [node, nodeNext]
}