给定一个异或链表和两个整数位置和值，任务是插入一个包含值的节点作为异或链表的第 th 个节点。
例子：
Input: 4<–>7<–>9<–>7, position = 3, value = 6
Output: 4<–>7<–>6<–>9<–>7
Explanation:
Inserting a node at the 3rd position with value 6 modifies the given XOR Linked List to 4<–>7<–>6<–>9<–>7.
Input: 4<–>7<–>9<–>7, position=6, value=6
Output: Invalid Position
Explanation: Since the given list consists of only 4 elements, 6th position is an invalid position in the given list.
处理方法：按照以下步骤解决问题：
- 初始化一个变量，比如ctr以保持在给定 XOR 链表中遍历的节点的计数。
- 遍历给定的 XOR 链表。对于异或链表的每个节点，检查当前节点的位置是否等于位置。如果发现为真，则将节点插入给定的 XOR 链表中。
- 否则，将ctr增加1 。
- 如果遍历整个列表并且未获得第一个节点的位置，则打印“无效位置” 。
下面是上述方法的实现：
C
// C++ program to implement
// the above approach
#include
#include
#include
// Structure of a node
// in XOR linked list
struct Node {
// Stores data value
// of a node
int data;
// Stores XOR of previous
// pointer and next pointer
struct Node* nxp;
};
// Function to find the XOR of two nodes
struct Node* XOR(struct Node* a,
struct Node* b)
{
return (struct Node*)((uintptr_t)(a)
^ (uintptr_t)(b));
}
// Function to insert a node with
// given value at given position
struct Node* insert(struct Node** head,
int value, int position)
{
// If XOR linked list is empty
if (*head == NULL) {
// If given position
// is equal to 1
if (position == 1) {
// Initialize a new Node
struct Node* node
= (struct Node*)malloc(
sizeof(struct Node));
// Stores data value in
// the node
node->data = value;
// Stores XOR of previous
// and next pointer
node->nxp = XOR(NULL, NULL);
// Update pointer of head node
*head = node;
}
// If required position was not found
else {
printf("Invalid Position\n");
}
}
// If the XOR linked list
// is not empty
else {
// Stores position of a node
// in the XOR linked list
int Pos = 1;
// Stores the address
// of current node
struct Node* curr = *head;
// Stores the address
// of previous node
struct Node* prev = NULL;
// Stores the XOR of next
// node and previous node
struct Node* next
= XOR(prev, curr->nxp);
// Traverse the XOR linked list
while (next != NULL && Pos < position - 1) {
// Update prev
prev = curr;
// Update curr
curr = next;
// Update next
next = XOR(prev, curr->nxp);
// Update Pos
Pos++;
}
// If the position of the current
// node is equal to the given position
if (Pos == position - 1) {
// Initialize a new Node
struct Node* node
= (struct Node*)malloc(
sizeof(struct Node));
// Stores pointer to previous Node
// as (prev ^ next ^ next) = prev
struct Node* temp
= XOR(curr->nxp, next);
// Stores XOR of prev and new node
curr->nxp = XOR(temp, node);
// Connecting new node with next
if (next != NULL) {
// Update pointer of next
next->nxp = XOR(node,
XOR(next->nxp, curr));
}
// Connect node with curr and
// next curr<--node-->next
node->nxp = XOR(curr, next);
node->data = value;
}
// Insertion node at beginning
else if (position == 1) {
// Initialize a new Node
struct Node* node
= (struct Node*)malloc(
sizeof(struct Node));
// Update curr node address
curr->nxp = XOR(node,
XOR(NULL, curr->nxp));
// Update new node address
node->nxp = XOR(NULL, curr);
// Update head
*head = node;
// Update data value of
// current node
node->data = value;
}
else {
printf("Invalid Position\n");
}
}
return *head;
}
// Function to print elements of
// the XOR Linked List
void printList(struct Node** head)
{
// Stores XOR pointer
// in current node
struct Node* curr = *head;
// Stores XOR pointer of
// in previous Node
struct Node* prev = NULL;
// Stores XOR pointer of
// in next node
struct Node* next;
// Traverse XOR linked list
while (curr != NULL) {
// Print current node
printf("%d ", curr->data);
// Forward traversal
next = XOR(prev, curr->nxp);
// Update prev
prev = curr;
// Update curr
curr = next;
}
}
// Driver Code
int main()
{
/* Create following XOR Linked List
head-->20<-->40<-->10<-->30 */
struct Node* head = NULL;
insert(&head, 10, 1);
insert(&head, 20, 1);
insert(&head, 30, 3);
insert(&head, 40, 2);
// Print the new list
printList(&head);
return (0);
} 输出：
20 40 10 30
时间复杂度： O(N)
辅助空间： O(1)
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