#707

Design Linked List

expert · 1165 · lc medium +32 · 29.9% accepted · 3,049 likes · top 7%

Description

Implement a linked list from scratch. You may use a singly or doubly linked list. Nodes are 0-indexed.

Implement the MyLinkedList class:

- MyLinkedList() Creates an empty linked list.

- int get(int index) Returns the value at position index, or -1 if the index is out of bounds.

- void addAtHead(int val) Inserts a node with value val at the front of the list.

- void addAtTail(int val) Appends a node with value val to the end of the list.

- void addAtIndex(int index, int val) Inserts a node with value val before the node at position index. If index equals the list length, appends to the end. If index exceeds the length, does nothing.

- void deleteAtIndex(int index) Removes the node at position index 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]

Example 2:

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

Code

class MyLinkedList:

    def __init__(self):
        

    def get(self, index: int) -> int:
        

    def addAtHead(self, val: int) -> None:
        

    def addAtTail(self, val: int) -> None:
        

    def addAtIndex(self, index: int, val: int) -> None:
        

    def deleteAtIndex(self, index: int) -> None:
        


# Your MyLinkedList object will be instantiated and called as such:
# obj = MyLinkedList()
# param_1 = obj.get(index)
# obj.addAtHead(val)
# obj.addAtTail(val)
# obj.addAtIndex(index,val)
# obj.deleteAtIndex(index)

class MyLinkedList:

    def __init__(self):
        

    def get(self, index: int) -> int:
        

    def addAtHead(self, val: int) -> None:
        

    def addAtTail(self, val: int) -> None:
        

    def addAtIndex(self, index: int, val: int) -> None:
        

    def deleteAtIndex(self, index: int) -> None:
        


# Your MyLinkedList object will be instantiated and called as such:
# obj = MyLinkedList()
# param_1 = obj.get(index)
# obj.addAtHead(val)
# obj.addAtTail(val)
# obj.addAtIndex(index,val)
# obj.deleteAtIndex(index)