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#include<iostream>
#include"../Seminar04/linked-list-utils.h"
using ListNode = LinkedListNode<int>;
ListNode* getNext(ListNode* head, int k) {
while(k && head) {
head = head->next;
--k;
}
return head;
}
ListNode* reverse(ListNode*& head) {
ListNode* next = nullptr;
ListNode* prev = nullptr;
ListNode* it = head;
ListNode* tmp = head;
while(it) {
next = it->next;
it->next = prev;
prev = it;
it = next;
}
head = prev;
return tmp;
}
ListNode* reverseKGroup(ListNode* head, int k) {
ListNode* end = getNext(head, k - 1);
if(end == nullptr)
return head;
ListNode* next = end->next;
end->next = nullptr;
ListNode* last = reverse(head);
ListNode* res = reverseKGroup(next, k);
last->next = res;
return head;
}
int main() {
ListNode* ll = fromList({1, 2, 3, 4, 5, 6, 7,8 ,9,10, 11, 12, 13, 14, 15, 16, 17});
ll = reverseKGroup(ll, 4);
printLinkedList(ll);
freeList(ll);
}
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