C ++程序以块方式旋转链表
给定一个长度为 n 和块长度为k的链表,每个块以循环方式向右/向左旋转一个数字d 。如果d为正,则向右旋转,否则向左旋转。
例子:
Input: 1->2->3->4->5->6->7->8->9->NULL,
k = 3
d = 1
Output: 3->1->2->6->4->5->9->7->8->NULL
Explanation: Here blocks of size 3 are
rotated towards right(as d is positive)
by 1.
Input: 1->2->3->4->5->6->7->8->9->10->
11->12->13->14->15->NULL,
k = 4
d = -1
Output: 2->3->4->1->6->7->8->5->10->11
->12->9->14->15->13->NULL
Explanation: Here, at the end of linked
list, remaining nodes are less than k, i.e.
only three nodes are left while k is 4.
Rotate those 3 nodes also by d.
先决条件:旋转链表
这个想法是如果 d 的绝对值大于 k 的值,则将链表旋转 d % k 次。如果 d 为 0,则根本不需要旋转链表。
C++
// C++ program to rotate a linked list
// block wise
#include
using namespace std;
// Link list node
class Node
{
public:
int data;
Node* next;
};
// Recursive function to rotate
// one block
Node* rotateHelper(Node* blockHead,
Node* blockTail,
int d, Node** tail,
int k)
{
if (d == 0)
return blockHead;
// Rotate Clockwise
if (d > 0)
{
Node* temp = blockHead;
for (int i = 1; temp->next->next &&
i < k - 1; i++)
temp = temp->next;
blockTail->next = blockHead;
*tail = temp;
return rotateHelper(blockTail, temp,
d - 1, tail, k);
}
// Rotate anti-Clockwise
if (d < 0)
{
blockTail->next = blockHead;
*tail = blockHead;
return rotateHelper(blockHead->next,
blockHead, d + 1,
tail, k);
}
}
// Function to rotate the linked list
// block wise
Node* rotateByBlocks(Node* head,
int k, int d)
{
// If length is 0 or 1 return head
if (!head || !head->next)
return head;
// if degree of rotation is 0,
// return head
if (d == 0)
return head;
Node* temp = head, *tail = NULL;
// Traverse upto last element of
// this block
int i;
for (i = 1; temp->next && i < k; i++)
temp = temp->next;
// Storing the first node of next block
Node* nextBlock = temp->next;
// If nodes of this block are less than k.
// Rotate this block also
if (i < k)
head = rotateHelper(head, temp,
d % k, &tail, i);
else
head = rotateHelper(head, temp,
d % k, &tail, k);
// Append the new head of next block to
// the tail of this block
tail->next = rotateByBlocks(nextBlock,
k, d % k);
// return head of updated Linked List
return head;
}
// UTILITY FUNCTIONS
// Function to push a node
void push(Node** head_ref,
int new_data)
{
Node* new_node = new Node;
new_node->data = new_data;
new_node->next = (*head_ref);
(*head_ref) = new_node;
}
// Function to print linked list
void printList(Node* node)
{
while (node != NULL)
{
cout << node->data << " ";
node = node->next;
}
}
// Driver code
int main()
{
// Start with the empty list
Node* head = NULL;
// Create a list 1->2->3->4->5->
// 6->7->8->9->NULL
for (int i = 9; i > 0; i -= 1)
push(&head, i);
cout <<
"Given linked list ";
printList(head);
// k is block size and d is number
// of rotations in every block.
int k = 3, d = 2;
head = rotateByBlocks(head, k, d);
cout <<
"Rotated by blocks Linked list ";
printList(head);
return (0);
}
// This is code is contributed by rathbhupendra
输出:
Given linked list
1 2 3 4 5 6 7 8 9
Rotated by blocks Linked list
2 3 1 5 6 4 8 9 7
有关详细信息,请参阅有关 Rotate Linked List 块的完整文章!