Design Singly Linked List

1class MyLinkedList:
2    def __init__(self):
3        self.head = None
4        self.size = 0
5
6    def get(self, index: int) -> int:
7        if index < 0 or index >= self.size:
8            return -1
9        cur = self.head
10        for _ in range(index):
11            cur = cur.next
12        return cur.val
13
14    def addAtHead(self, val: int) -> None:
15        node = ListNode(val)
16        node.next = self.head
17        self.head = node
18        self.size += 1
19
20    def addAtTail(self, val: int) -> None:
21        node = ListNode(val)
22        if not self.head:
23            self.head = node
24        else:
25            cur = self.head
26            while cur.next:
27                cur = cur.next
28            cur.next = node
29        self.size += 1
30
31    def addAtIndex(self, index: int, val: int) -> None:
32        if index < 0 or index > self.size:
33            return
34        if index == 0:
35            self.addAtHead(val)
36            return
37        cur = self.head
38        for _ in range(index - 1):
39            cur = cur.next
40        node = ListNode(val)
41        node.next = cur.next
42        cur.next = node
43        self.size += 1
44
45    def deleteAtIndex(self, index: int) -> None:
46        if index < 0 or index >= self.size:
47            return
48        if index == 0:
49            self.head = self.head.next
50            self.size -= 1
51            return
52        cur = self.head
53        for _ in range(index - 1):
54            cur = cur.next
55        cur.next = cur.next.next
56        self.size -= 1