Design your implementation of the linked list. You can choose to use a singly or doubly linked list.
A node in a singly linked list should have two attributes: val and next. val is the value of the current node, and next is a pointer/reference to the next node.
If you want to use the doubly linked list, you will need one more attribute prev to indicate the previous node in the linked list. Assume all nodes in the linked list are 0-indexed.
Implement the MyLinkedList class:
MyLinkedList() Initializes the MyLinkedList object.int get(int index) Get the value of the indexth node in the linked list. If the index is invalid, return -1.void addAtHead(int val) Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list.void addAtTail(int val) Append a node of value val as the last element of the linked list.void addAtIndex(int index, int val) Add a node of value val before the indexth node in the linked list. If index equals the length of the linked list, the node will be appended to the end of the linked list. If index is greater than the length, the node will not be inserted.void deleteAtIndex(int index) Delete the indexth node in the linked list, if the index is valid.
Example 1:
Input ["MyLinkedList", "addAtHead", "addAtTail", "addAtIndex", "get", "deleteAtIndex", "get"] [[], [1], [3], [1, 2], [1], [1], [1]] Output [null, null, null, null, 2, null, 3] Explanation MyLinkedList myLinkedList = new MyLinkedList(); myLinkedList.addAtHead(1); myLinkedList.addAtTail(3); myLinkedList.addAtIndex(1, 2); // linked list becomes 1->2->3 myLinkedList.get(1); // return 2 myLinkedList.deleteAtIndex(1); // now the linked list is 1->3 myLinkedList.get(1); // return 3
Constraints:
0 <= index, val <= 10002000 calls will be made to get, addAtHead, addAtTail, addAtIndex and deleteAtIndex.In this approach, you will design a singly linked list where each node has a value and a pointer to the next node. This type of list is simple and efficient for certain operations, especially when traversing only forwards is sufficient.
The above code implements a singly linked list in C. It provides functions to add nodes at the head, tail, a specific index, get the value at an index, and delete a node at an index. The linked list maintains a head pointer and nodes are dynamically allocated using malloc.
C++
Java
Python
C#
JavaScript
Time Complexity:
- get: O(n)
- addAtHead: O(1)
- addAtTail: O(n)
- addAtIndex: O(n)
- deleteAtIndex: O(n)
Space Complexity: O(n), where n is the number of nodes in the list.
This approach designs a doubly linked list, allowing traversal both forwards and backwards. Each node maintains a reference to both the next and previous node, facilitating operations such as adding or removing nodes from either end more efficiently.
The C implementation of a doubly linked list adds a prev pointer to each node, enabling two-way node traversal and efficient deletion and insertion operations from both ends.
C++
Java
Python
C#
JavaScript
Time Complexity:
- get: O(n)
- addAtHead: O(1)
- addAtTail: O(n)
- addAtIndex: O(n)
- deleteAtIndex: O(n)
Space Complexity: O(n), where n is the number of nodes in the list.
| Approach | Complexity |
|---|---|
| Singly Linked List Implementation | Time Complexity: |
| Doubly Linked List Implementation | Time Complexity: |
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