Description
Given the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences.
After doing so, return the head of the final linked list. You may return any such answer.
(Note that in the examples below, all sequences are serializations of ListNode objects.)
Example 1:
Input: head = [1,2,-3,3,1] Output: [3,1] Note: The answer [1,2,1] would also be accepted.
Example 2:
Input: head = [1,2,3,-3,4] Output: [1,2,4]
Example 3:
Input: head = [1,2,3,-3,-2] Output: [1]
Constraints:
- The given linked list will contain between
1and1000nodes. - Each node in the linked list has
-1000 <= node.val <= 1000.
Solution
Python3
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, val=0, next=None):
# self.val = val
# self.next = next
class Solution:
def removeZeroSumSublists(self, head: ListNode) -> ListNode:
curr = 0
seen = {}
dummy = ListNode(0, head)
seen[0] = dummy
while head:
curr += head.val
seen[curr] = head
head = head.next
curr = 0
head = dummy
while head:
curr += head.val
head.next = seen[curr].next
head = head.next
return dummy.next