题解 | #链表内指定区间反转#
链表内指定区间反转
https://www.nowcoder.com/practice/b58434e200a648c589ca2063f1faf58c
/** * struct ListNode { * int val; * struct ListNode *next; * ListNode(int x) : val(x), next(nullptr) {} * }; */ class Solution { public: /** * 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可 * * * @param head ListNode类 * @param m int整型 * @param n int整型 * @return ListNode类 */ ListNode* reverseBetween(ListNode* head, int m, int n) { // write code here if(!head || !head->next || n-m < 1) return head; ListNode LL = ListNode(-1); ListNode* PreHead = &LL; PreHead->next = head; ListNode* rePre = PreHead; ListNode* reNext = head->next; for(int i=1; i< n; i++){ if(i < m) rePre = rePre->next; reNext = reNext->next; } ListNode* Phead = rePre->next,*temp = nullptr,*Pre = reNext; for (int i=0; i<n-m + 1; i++) { temp = Phead->next; Phead->next= Pre; Pre = Phead; Phead = temp; } rePre->next = Pre; return PreHead->next; } };