count = total
minus = 0
while count and not que.empty():
node = que.get()
level.append(node.val)
if node.left:
que.put(node.left)
else:
minus += 1
if node.right:
que.put(node.right)
else:
minus += 1
count -= 1
ans.append(level[:])
level.clear()
total = total * 2 - minus
return ans
if __name__ == '__main__':
tree = '[3,9,20,null,null,15,7]'
root = deserialize(tree)
drawtree(root)
ans = Solution().levelOrder(root)
print(ans)
rightRes = self.inOrder(root.right)
# 不能用如下表达式
# res = leftRes or rightRes
res = leftRes if leftRes != None else rightRes
return res
def createListByLevel(arr):
end = len(arr)
index = 0
nodes = [TreeNode(val) if val != None else None for val in arr]
while index * 2 + 1 < end:
if nodes[index] != None:
nodes[index].left = nodes[index * 2 + 1]
if index * 2 + 2 < end:
nodes[index].right = nodes[index * 2 + 2]
index += 1
return nodes[0]
if __name__ == '__main__':
#arr = [5, 3, 6, 2, 4, None, None, 1]
#arr = [31,30,48,3,None,38,49,0,16,35,47,None,None,None,2,15,27,33,37,39,None,1,None,5,None,22,28,32,34,36,None,None,43,None,None,4,11,19,23,None,29,None,None,None,None,None,None,40,46,None,None,7,14,17,21,None,26,None,None,None,41,44,None,6,10,13,None,None,18,20,None,25,None,None,42,None,45,None,None,8,None,12,None,None,None,None,None,24,None,None,None,None,None,None,9]
# 这个测试用例主要是0的判断, 所以return时不能用 a or b表达式
root = deserialize(
'[31,30,48,3,null,38,49,0,16,35,47,null,null,null,2,15,27,33,37,39,null,1,null,5,null,22,28,32,34,36,null,null,43,null,null,4,11,19,23,null,29,null,null,null,null,null,null,40,46,null,null,7,14,17,21,null,26,null,null,null,41,44,null,6,10,13,null,null,18,20,null,25,null,null,42,null,45,null,null,8,null,12,null,null,null,null,null,24,null,null,null,null,null,null,9]'
)
ans = Solution().kthSmallest(root, 1)
print(ans)
def lowestCommonAncestor(self, root, p, q):
"""
:type root: TreeNode
:type p: TreeNode
:type q: TreeNode
:rtype: TreeNode
"""
if root is None or root.val == p.val or root.val == q.val:
return root
left = self.lowestCommonAncestor(root.left, p, q)
right = self.lowestCommonAncestor(root.right, p, q)
if left is not None and right is not None:
return root
# return the node that is not none or None
return left if left is not None else right
if __name__ == '__main__':
tree = deserialize('[1,2,3,4,5,6,7]')
res = Solution().lowestCommonAncestor(tree, TreeNode(4), TreeNode(5))
print(res)
tree = deserialize('[1,2,null,3,null,4,null,5]')
res = Solution().lowestCommonAncestor(tree, TreeNode(4), TreeNode(5))
print(res)
def isValidBST(self, root):
self.prev = None
return self.doValidBST(root)
def doValidBST(self, root):
"""
:type root: TreeNode
:rtype: bool
"""
if root is None:
return True
if not self.doValidBST(root.left):
return False
if self.prev is not None and root.val <= self.prev.val:
return False
self.prev = root
return self.doValidBST(root.right)
if __name__ == '__main__':
root = deserialize('[6,3,8,1,4,7,9]')
drawtree(root)
res = Solution().isValidBST(root)
print(res)
# self.val = x
# self.left = None
# self.right = None
# self.next = None
from tools.leetcode import deserialize
class Solution:
# @param root, a tree link node
# @return nothing
def connect(self, root):
if root is None:
return None
if root.left and root.right:
root.left.next = root.right
connLeft = root.right if root.right is not None else root.left
if connLeft and root.next:
connRight = root.next.left if root.next.left else root.next.right
connLeft.next = connRight
self.connect(root.left)
self.connect(root.right)
if __name__ == '__main__':
tree = deserialize('[1,2,3,4,5,6,7]')
Solution().connect(tree)
print(tree)
class Solution:
def isSymmetric(self, root):
"""
:type root: TreeNode
:rtype: bool
"""
if root is None:
return True
return self.doSymmetricRecursive(root.left, root.right)
def doSymmetricRecursive(self, nodeLeft, nodeRight):
if nodeLeft is None and nodeRight is None:
return True
if nodeLeft is None or nodeRight is None:
return False
if nodeLeft.val == nodeRight.val:
outPair = self.doSymmetricRecursive(nodeLeft.left, nodeRight.right)
inPair = self.doSymmetricRecursive(nodeLeft.right, nodeRight.left)
return inPair and outPair
return False
if __name__ == '__main__':
nodes = '[1,2,2,3,4,4,3]'
nodes = '[1,2,2,null,3,null,3]'
root = deserialize(nodes)
res = Solution().isSymmetric(root)
print(res)
class Solution:
def TwoNodesFather(self, head, n1, n2):
if head is None or head.val == n1 or head.val == n2:
return head
left = self.TwoNodesFather(head.left, n1, n2)
right = self.TwoNodesFather(head.right, n1, n2)
if left is not None and right is not None:
return head
return left if left is not None else right
if __name__ == '__main__':
tree = deserialize('[1, 2, 3, 4, 5, 6, 7]')
drawtree(tree)
print(Solution().TwoNodesFather(tree, 4, 5))
tree = deserialize('[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]')
#drawtree(tree)
print(Solution().TwoNodesFather(tree, 4, 5))
tree = deserialize('[1,2,null,3,null,4]')
drawtree(tree)
print(Solution().TwoNodesFather(tree, 4, 3))