level = 0
while len(current) > 0:
future = []
temp = []
for i in range(len(current)):
node = current[i]
if node:
temp.append(node.val)
future.append(node.left)
future.append(node.right)
if temp and level % 2 == 0:
ans.append(temp)
elif temp and level % 2 == 1:
ans.append((temp[-1::-1]))
current = future
level += 1
return ans
codec = Codec()
root = codec.deserialize("3,9,20,None,None,15,7")
assert Solution().zigzagLevelOrder(root) == [[3], [20, 9], [15, 7]]
def itr(root):
if not root:
return
itr(root.left)
self.lst.append(root.val)
itr(root.right)
itr(root)
def next(self) -> int:
"""
@return the next smallest number
"""
return self.lst.pop(0)
def hasNext(self) -> bool:
"""
@return whether we have a next smallest number
"""
return len(self.lst) > 0
root = Codec().deserialize("7,3,15,None,None,9,20")
# Your BSTIterator object will be instantiated and called as such:
obj = BSTIterator(root)
v = []
while obj.hasNext():
v.append(obj.next())
assert (v == [3, 7, 9, 15, 20])
self.val = val
self.left = left
self.right = right
class Solution:
def diameterOfBinaryTree(self, root: TreeNode) -> int:
if not root:
return 0
def get_height(root):
if not root:
return 0
return 1 + max(get_height(root.left), get_height(root.right))
lh = get_height(root.left)
rh = get_height(root.right)
rdd = lh + rh
ld = self.diameterOfBinaryTree(root.left)
rd = self.diameterOfBinaryTree(root.right)
return max(rdd, max(ld, rd))
c = Codec()
root = c.deserialize("1,2,3,4,5")
print(Solution().diameterOfBinaryTree(root))
# Definition for a binary tree node.
from problems.lc_297 import Codec
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
class Solution:
def str2tree(self, s: str) -> TreeNode:
def getnum(str):
sign = 1
if str[0] == "-":
sign =-1
codec = Codec()
node = codec.deserialize("4,2,3,1,6,5")
assert Solution().str2tree("4(2(3)(1))(6(5))") == node
while len(lst_even) > 0 or len(lst_odd) > 0:
if odd:
current_lst = lst_odd
next_lst = lst_even
else:
current_lst = lst_even
next_lst = lst_odd
element = current_lst.pop(0)
if element and element.left:
next_lst.append(element.left)
if element and element.right:
next_lst.append(element.right)
if len(current_lst) == 0:
res.append(element.val)
odd = not odd
return res
codec = Codec()
# str1= "1,2,3,None,5,None,4"
# node = codec.deserialize(str1)
# print(Solution().rightSideView(node))
str1 = "1,2,3,4"
node = codec.deserialize(str1)
print(Solution().rightSideView(node))
print("done")
def isValidBST(self, node):
return self._isValidBST(node, sys.maxsize, - sys.maxsize -1)
def _isValidBST(self, node, l, u):
if not node:
return True
if node.left and not self._checkbound(node.left.value, l, node.value):
return False
if node.right and not self._checkbound(node.right.value, node.value, u):
return False
if not self.isValidBST(node.left) or not self.isValidBST(node.right):
return False
return True
def _checkbound(self, n, l, u):
if l <= n and n <= u:
return True
return False
codec = Codec()
root = codec.deserialize("7,3,10,1,4,8,11")
assert(Solution().isValidBST(root) == True)
tree = build_binary_tree("2,1,1,1")
assert(Solution().isValidBST(tree) == False)
if root and root.left:
stack.append(root.left)
root.left = None
elif root:
ans.append(root.val)
if k == len(ans):
return ans[-1]
stack.pop()
if root.right:
stack.append(root.right)
else:
stack.pop()
codec = Codec()
root = codec.deserialize(
"41,37,44,24,39,42,48,1,35,38,40,null,43,46,49,0,2,30,36,null,null,null,null,null,null,45,47,null,null,null,null,null,4,29,32,null,null,null,null,null,null,3,9,26,null,31,34,null,null,7,11,25,27,null,null,33,null,6,8,10,16,null,null,null,28,null,null,5,null,null,null,null,null,15,19,null,null,null,null,12,null,18,20,null,13,17,null,null,22,null,14,null,null,21,23"
)
assert (Solution().kthSmallest(root, 25) == 24)
root = codec.deserialize("1")
assert (Solution().kthSmallest(root, 1) == 1)
root = codec.deserialize("3,1,4,None,2")
assert (Solution().kthSmallest(root, 1) == 1)
root = codec.deserialize("5,3,6,2,4,None,None,1")
assert (Solution().kthSmallest(root, 3) == 3)
inorder(root.left)
node = Node(root.val)
node.left = last
if head is None:
head = node
if last is not None:
last.right = node
last = node
inorder(root.right)
inorder(root)
if last:
last.right = head
if head:
head.left = last
return head
codec = Codec()
root = codec.deserialize("4,2,5,1,3")
val = Solution().treeToDoublyList(root)
root = codec.deserialize("4,2,5,1,3")
val = Solution().treeToDoublyList(root)
print("done")
class Solution:
def inorderTraversal(self, root: TreeNode) -> List[int]:
stack = [root]
ans = []
while len(stack) > 0:
root = stack[-1]
if root and root.left:
stack.append(root.left)
root.left = None
elif root:
ans.append(root.val)
stack.pop()
if root.right:
stack.append(root.right)
else:
stack.pop()
return ans
codec = Codec()
root = codec.deserialize("1,None,2,3")
assert Solution().inorderTraversal(root) == [1, 3, 2]
return c
elif parent is not None:
return parent
else:
return None
a = find(root.left, p, root)
if a is not None:
return a
b = find(root.right, p, parent)
if b is not None:
return b
return find(root, p, None)
codec = Codec()
root = codec.deserialize("6,2,8,0,4,7,9,null,null,3,5")
assert Solution().inorderSuccessor(root, TreeNode(2)).val == 3
root = codec.deserialize("5,3,6,1,4,null,null,null,2")
assert Solution().inorderSuccessor(root, TreeNode(4)).val == 5
root = codec.deserialize("2,1,3")
assert Solution().inorderSuccessor(root, TreeNode(1)).val == 2
root = codec.deserialize("5,3,6,2,4,null,null,1")
assert Solution().inorderSuccessor(root, TreeNode(6)) == None