题解 | #链表中的节点每k个一组翻转#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @param k int整型 
     * @return ListNode类
     */
    ListNode* reverseKGroup(ListNode* head, int k) {
        // write code here
        ListNode* hail = new ListNode(0);
        hail->next = head;
        ListNode* slow = hail;
        ListNode* fast = hail;
        ListNode* temp1;
        
        while(fast != nullptr){
            for(int i=0; i<k; i++){
                if(fast != nullptr){
                    fast = fast->next;
                }
            }
            if(fast == nullptr){
                break;
            }
            temp1 = slow->next;
            slow->next = reverseList(slow->next, fast);
            slow = temp1;
            fast = temp1;
        }
        
        return hail->next;
    }
    
    ListNode* reverseList(ListNode* slow, ListNode* fast){
        ListNode* pre = fast->next;
        ListNode* post = nullptr;
        ListNode* cur = slow;
        while(pre != fast){
            post = cur->next;
            cur->next = pre;
            pre = cur;
            cur = post;
        }
        return pre;
    }
    
};