Leetcode---92. Reverse Linked List II

Title Link: Reverse Linked List II

Reverse a linked list from position m to N. Do it in-place and in One-pass.

For example:

Given 1->2->3->4->5->null, M = 2 and n = 4,

Return 1->4->3->2->5->null.

Note:

Given m, n satisfy the following condition:

1≤m≤n≤length of the list.

The requirement of this problem is to reverse the M-n position in the list.

chain list processing, first add an empty table header, easy to handle. The l pointer is then moved to the front of the m position so that R moves to the M position, which constantly inserts the nodes behind R into the L until the n position.

Assuming m=2,n=4, the linked list is: Head--1, 2, 3, 4, 5---------0--1, 2          5. Null to move the L pointer to the M position before moving R to the m position, i.e., 0, 1, 2    |          |    L The node behind the RR is inserted into the back of L: listnode *temp = L--next:h, 0, 1, 2, 3, 4    ^          |          |          L TEMP, R L-next = R-Next: |-------->|h, 0, 1 2, 3, 4    ^    ^          |          | L TEMP, rr-next = Next Next: |-------->|h, 0, 1 2 3, 4, 5,          NULL ^ |-------->|    |             ^ L |          Temp, RL, next, Next = temp: |-------->|h, 0, 1 2 <-3 4, 5--NULL          ^ |-------->|    |             ^ L | Temp, R: 1, 0, H--3->         2, 4, 5, NULL ^ ^ |          | L R then continue to insert the R back node behind L, and so on, loop ...

Time complexity: O (N)

Space complexity: O (1)

1 class Solution2 {3  Public:4     ListNode *Reversebetween(ListNode *Head, int m, int N)5     {6         ListNode *h = New ListNode(0);7         h  - Next = Head;8         9         ListNode *L = h, *R;Ten          for(int I = 1; I < m; ++ I) One             L = L  - Next; A          -         R = L  - Next; -          for(int I = 1; I < N - m + 1; ++ I) the         { -             ListNode *Temp = L  - Next; -             L  - Next = R  - Next; -             R  - Next = R  - Next  - Next; +             L  - Next  - Next = Temp; -         } +          A         return h  - Next; at     } - };

Reprint please indicate source: Leetcode---92. Reverse Linked List II

Leetcode---92. Reverse Linked List II