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#include "leetcode.h"
class Solution {
public:
ListNode *reverseBetween(ListNode *head, int left, int right) {
if (head == NULL || head->next == NULL)
return head;
ListNode *tmp = new ListNode(-1);
tmp->next = head;
ListNode *itL = tmp, *preL = NULL;
for (int i = 0; i < left; i++) {
preL = itL;
itL = itL->next;
}
ListNode *itR = itL, *preR = preL;
for (int i = left; i <= right; i++) {
ListNode *forward = itR->next;
itR->next = preR;
preR = itR;
itR = forward;
}
preL->next = preR;
itL->next = itR;
return tmp->next;
}
};
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