"""
# Definition for a Node.
class Node:
def __init__(self, val: int = 0, left: 'Node' = None, right: 'Node' = None, next: 'Node' = None):
self.val = val
self.left = left
self.right = right
self.next = next
"""
class Solution:
def connect(self, root: 'Node') -> 'Node':
if not root:
return
dq = deque([root])
while dq:
levelSize = len(dq)
for nodeIdx in range(levelSize):
currNode = dq.popleft()
if nodeIdx != levelSize - 1:
currNode.next = dq[0]
if currNode.left:
dq.append(currNode.left)
if currNode.right:
dq.append(currNode.right)
return(root)