def buildTree(l, r):
if l > r:
return None
mid = (l + r) // 2
root = TreeNode(mem[mid])
root.left = buildTree(l, mid - 1)
root.right = buildTree(mid + 1, r)
return root
def buildSub(l1, r1, l2, r2):
# print(l1, r1, l2, r2)
if l1 > r1:
return None
root = TreeNode(preorder[l1])
if l1 == r1:
return root
nr = preorder[l1 + 1]
i = l2
while postorder[i] != nr:
i += 1
root.left = buildSub(l1 + 1, l1 + 1 + (i - l2), l2, i)
root.right = buildSub(l1 + 1 + (i - l2) + 1, r1, i + 1, r2 - 1)
return root
out.append([])
while len(stack1) > 0:
node = stack1.pop()
out[-1].append(node.val)
if node.left != None:
stack2.append(node.left)
if node.right != None:
stack2.append(node.right)
if len(stack2) == 0:
break
out.append([])
while len(stack2) > 0:
node = stack2.pop()
out[-1].append(node.val)
if node.right != None:
stack1.append(node.right)
if node.left != None:
stack1.append(node.left)
return out
sl = Solution()
root = TreeNode(3)
root.left = TreeNode(9)
root.left.left = TreeNode(1)
root.left.right = TreeNode(3)
root.right = TreeNode(20)
root.right.left = TreeNode(15)
root.right.right = TreeNode(7)
print(sl.zigzagLevelOrder(root))
from typing import *
from pytree import TreeNode
class Solution:
def countNodes(self, root: TreeNode) -> int:
if root==None:
return 0
return 1+self.countNodes(root.left)+self.countNodes(root.right)
sl=Solution()
# 1
# / \
# 2 3
# / \ /
# 4 5 6
root=TreeNode(1)
root.left=TreeNode(2)
root.left.left=TreeNode(4)
root.left.right=TreeNode(5)
root.right=TreeNode(3)
root.right.left=TreeNode(6)
print(sl.countNodes(root))
