day38（12.19）——leetcode面试经典150

92. 反转链表 II

92. 反转链表Ⅱ

题目：

题解：

/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode() {} * ListNode(int val) { this.val = val; } * ListNode(int val, ListNode next) { this.val = val; this.next = next; } * } */ class Solution { public ListNode reverseBetween(ListNode head, int left, int right) { ListNode cur = head; ListNode part = new ListNode(); int count = 1; Map<Integer, ListNode> map = new HashMap<>(); while(cur != null) { map.put(count++, new ListNode(cur.val)); cur = cur.next; } cur = new ListNode(); ListNode h = cur; for(int i=1;i<left;i++) { cur.next = map.get(i); cur = cur.next; } for(int i=right;i>=left;i--) { cur.next = map.get(i); cur = cur.next; } for(int i=right+1;i<count;i++) { cur.next = map.get(i); cur = cur.next; } return h.next; } }