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; * }; */ /** * 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 */ struct ListNode* reverseBetween(struct ListNode* head, int m, int n ) { // write code here //找位置 if(m == n) { return head; } struct ListNode* first = head; struct ListNode* last = head; struct ListNode* first_front = head; struct ListNode* last_behind = head; int i = 1; while(first) //找头 { if(i == m) { break; } i++; first_front = first; first = first->next; } last = first; while(last) //找尾 { if(i == n) { last_behind = last->next; break; } i++; last = last->next; } struct ListNode* front = first; struct ListNode* behind = first; struct ListNode* final = first; while(front != last) { if(front == first) { behind = front->next; final = behind->next; if(last->next == NULL) //当n为最后一个结点时 { front->next = NULL; } else { front->next = last_behind; } behind->next = front; } else { behind->next = front; } front = behind; behind = final; if(behind != NULL) { final = final->next; } } if(first == head) //当m为第一个结点时 { head = last; } else { first_front->next = last; } return head; }