19.2.24 [LeetCode 92] Reverse Linked List II
Reverse a linked list from position m to n. Do it in one-pass.
Note: 1 ≤ m ≤ n ≤ length of list.
Example:
Input: 1->2->3->4->5->NULL, m = 2, n = 4
Output: 1->4->3->2->5->NULL
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 class Solution { 2 public: 3 ListNode* reverseBetween(ListNode* head, int m, int n) { 4 ListNode*mnode = head, *nnode = head, *bef = NULL, *aft = NULL, *now = head; 5 int cnt = 1; 6 while (now) { 7 if (cnt == m - 1) 8 bef = now; 9 else if (cnt == m) 10 mnode = now; 11 if (cnt == n) { 12 nnode = now; 13 aft = nnode->next; 14 break; 15 } 16 now = now->next; 17 cnt++; 18 } 19 nnode->next = NULL; 20 if(bef) 21 bef->next = NULL; 22 while (mnode) { 23 ListNode*next = mnode->next; 24 mnode->next = aft; 25 aft = mnode, mnode = next; 26 } 27 if (bef) { 28 bef->next = nnode; 29 return head; 30 } 31 return nnode; 32 } 33 };
注定失败的战争,也要拼尽全力去打赢它;
就算输,也要输得足够漂亮。