[leetcode] Reverse Linked List II
题目:(LinkedList)
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.
题解:
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { * val = x; * next = null; * } * } */ public class Solution { public ListNode reverseBetween(ListNode head, int m, int n) { ListNode fakeHead = new ListNode(0); fakeHead.next = head ; if(head==null||head.next==null) return fakeHead.next; ListNode prev = fakeHead; ListNode curr = null; ListNode last = null; for(int i=0; i<n; i++) { if(i<m-1) { prev=prev.next; } else if(i==m-1) { last=prev.next; curr=last.next; } else { last.next=curr.next; curr.next=prev.next; prev.next=curr; curr=last.next; } } return fakeHead.next; } }
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