题解 | #链表中的节点每k个一组翻转#

import java.util.*;

/*

• public class ListNode {
• int val;
• ListNode next = null;
• } */

public class Solution { /** * * @param head ListNode类 * @param k int整型 * @return ListNode类 */ public ListNode reverseKGroup (ListNode head, int k) { if(head == null){ return null; } ListNode temp = head; return dfs(temp,k); } ListNode dfs(ListNode root,int k){ if(root == null){ return null; } ListNode prev = null; ListNode cur = root; ListNode next = root; ListNode temp = root; int count = k; while(temp != null && count > 0){ temp = temp.next; count--; } if(count > 0){ return root; } ListNode h = temp; int a = k; while(next != null && a > 0){ next = cur.next; cur.next = prev; prev = cur; cur = next; a--; } root.next = dfs(h,k); return prev; } }