from typing import List
from tools import TreeNode
class Solution:
def largestValues(self, root: TreeNode) -> List[int]:
if root is None:
return []
result = []
queue = [root]
while len(queue) > 0:
maxValue = None
length = len(queue)
for i in range(length):
node = queue.pop(0)
if maxValue is None or maxValue < node.val:
maxValue = node.val
if node.left is not None:
queue.append(node.left)
if node.right is not None:
queue.append(node.right)
result.append(maxValue)
return result
print(Solution().largestValues(TreeNode.stringToTreeNode("[1,3,2,5,3,9]")))
from tools import TreeNode
class Solution:
def hasPathSum(self, root: TreeNode, sum: int) -> bool:
if root is None:
return False
return self._addValEqual(root, 0, sum)
def _addValEqual(self, node, counter, sum):
if node is None:
return counter == sum
counter += node.val
haveChild = False
if node.left is not None:
haveChild = True
if self._addValEqual(node.left, counter, sum):
return True
if node.right is not None:
haveChild = True
if self._addValEqual(node.right, counter, sum):
return True
return False if haveChild else counter == sum
print(Solution().hasPathSum(TreeNode.stringToTreeNode("[0,1,1]"), 0))
from tools import TreeNode
class Solution:
def isValidBST(self, root: TreeNode) -> bool:
if root is None:
return True
return self.dfs(root, None) is not None
def dfs(self, root, before):
last = None
if root.left is not None:
temp = self.dfs(root.left, before)
if temp is None or temp >= root.val:
return None
if before is None or root.val > before:
last = root.val
else:
return None
if root.right is not None:
temp = self.dfs(root.right, last)
if temp is None or temp <= root.val:
return None
last = temp
return last
print(Solution().isValidBST(
TreeNode.stringToTreeNode("[5,1,4,null,null,3,6]")))
from tools import TreeNode
class Solution:
def pruneTree(self, root: TreeNode) -> TreeNode:
if root is None:
return None
self.doPruneTree(root)
return root
def doPruneTree(self, root):
flag = False
if root.left is not None:
x = self.doPruneTree(root.left)
if not x:
root.left = None
flag = flag or x
if root.right is not None:
x = self.doPruneTree(root.right)
if not x:
root.right = None
flag = flag or x
return flag or (root.val == 1)
print(TreeNode.treeNodeToString(Solution().pruneTree(TreeNode.stringToTreeNode("[1,null,0,0,1]"))))
from typing import List
from tools import TreeNode
class Solution:
def levelOrder(self, root: TreeNode) -> List[List[int]]:
if root is None:
return []
result = []
queue = [root]
while len(queue) > 0:
length = len(queue)
temp = [0] * length
for i in range(length):
node = queue.pop(0)
temp[i] = node.val
if node.left is not None:
queue.append(node.left)
if node.right is not None:
queue.append(node.right)
result.append(temp)
return result
print(Solution().levelOrder(
TreeNode.stringToTreeNode("[3,9,20,null,null,15,7]")))
from tools import TreeNode
class Solution:
def findTilt(self, root: TreeNode) -> int:
if root is None:
return 0
result = [0]
self.getSum(root, result)
return result[0]
def getSum(self, root, num):
sumLeft = 0
sumRight = 0
if root.left is not None:
sumLeft = self.getSum(root.left, num)
if root.right is not None:
sumRight = self.getSum(root.right, num)
num[0] = num[0] + abs(sumLeft - sumRight)
return sumLeft + sumRight + root.val
root = TreeNode.stringToTreeNode("[1,2,3]")
print(Solution().findTilt(root))
