Leetcode/leetcode25.cpp at main · ksaini-web/Leetcode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* reverseKGroup(ListNode* head, int k) {

        ListNode* temp = head;

        int cnt = 0;

        while(cnt<k){

            if(temp ==NULL){
                return head;
                }

            temp=temp->next;
            cnt++;
        }
        ListNode* prevNode = reverseKGroup(temp,k);
         temp=head ;cnt=0;
        while(cnt<k){

           ListNode* next= temp->next;

           temp->next=prevNode;

           prevNode=temp;

           temp=next;

           cnt++;


        }

        return prevNode;
    }
};