I'm working on this problem: https://leetcode.com/explore/learn/card/linked-list/209/singly-linked-list/1290/
and leetcode is telling me that my code is throwing a runtime error. The input it's trying to make my code run is this:
["MyLinkedList","addAtHead","deleteAtIndex","addAtHead","addAtHead","addAtHead","addAtHead","addAtHead","addAtTail","get","deleteAtIndex","deleteAtIndex"]
[[],[2],[1],[2],[7],[3],[2],[5],[5],[5],[6],[4]]
Where the first array contains the function name and the second contains the function parameters. E.g. the second element adds a 2 at the head of the linkedlist. My question is that how would it be OK to be deleting the element at index 1 when there is only one element in the linkedlist? Is there some special thing about linked lists that I should know or is the input case incorrect. Below is my code for reference.
class SinglyLinkedList():
def __init__(self):
self.head = None
self.tail = None
self.length = 0
def get(self, index):
if index<0 or index>self.length: raise AssertionError("get index must be in bounds")
node = self.head
for _ in range(index):
node = node.next
return node
def addAtHead(self, val):
node = SinglyListNode(val)
if self.length==0:
self.head = node
self.tail = self.head
else:
node.next = self.head
self.head = node
self.length+=1
def addAtTail(self, val):
node = SinglyListNode(val)
if self.length==0:
self.tail = node
self.head = self.tail
else:
self.tail.next = node
self.tail = node
self.length+=1
def addAtIndex(self, index, val):
if index<0 or index>self.length:
raise AssertionError(f"index at which to add ({index}) is out of bounds")
if index==0:
return self.addAtHead(val)
if index==self.length:
return self.addAtTail(val)
newNode = SinglyListNode(val)
node = self.head
for _ in range(index-1):
node = node.next
newNode.next = node.next
node.next = newNode
self.length+=1
def deleteAtIndex(self, index):
if index<0 or index>self.length:
raise AssertionError(f"index at which to add ({index}) is out of bounds")
if index==0:
self.head = self.head.next
elif index==self.length-1:
self.tail=self.get(self.length-2)
else:
node = self.head
for _ in range(index-1):
node = node.next
node.next = node.next.next
self.length-=1
def __str__(self):
res = "["
node = self.head
for _ in range(self.length-1):
res += str(node)+","
node = node.next
res += str(node)+f"] ({self.length})"
return res
