def helper(root, v, d, level):
if not root:
return
if level + 1 == d:
node_left = TreeNode(v)
node_left.left = root.left
root.left = node_left
node_right = TreeNode(v)
node_right.right = root.right
root.right = node_right
return
helper(root.left, v, d, level + 1)
helper(root.right, v, d, level + 1)
def addOneRow(self, root, v, d):
"""
:type root: TreeNode
:type v: int
:type d: int
:rtype: TreeNode
"""
def helper(root, v, d, level):
if not root:
return
if level + 1 == d:
node_left = TreeNode(v)
node_left.left = root.left
root.left = node_left
node_right = TreeNode(v)
node_right.right = root.right
root.right = node_right
return
helper(root.left, v, d, level + 1)
helper(root.right, v, d, level + 1)
if d == 1:
node = TreeNode(v)
node.left = root
return node
helper(root, v, d, 1)
return root
def reConstructBinaryTree(self, pre, tin):
if len(pre) == 0:
return
root = TreeNode(pre[0])
tinIndex = tin.index(pre[0])
root.left = self.reConstructBinaryTree(pre[1:tinIndex + 1],
tin[:tinIndex])
root.right = self.reConstructBinaryTree(pre[tinIndex + 1:],
tin[tinIndex + 1:])
return root
def dfs(self, left, right):
res = []
if left > right:
return [None]
for i in range(left, right+1):
left_nodes = self.dfs(left, i-1)
right_nodes = self.dfs(i+1, right)
for left_node in left_nodes:
for right_node in right_nodes:
node = TreeNode(i)
node.left = left_node
node.right = right_node
res.append(node)
return res
def buildTree(self, inorder, postorder):
"""
:type inorder: List[int]
:type postorder: List[int]
:rtype: TreeNode
"""
if not postorder:
return None
root = TreeNode(postorder[-1]) # 后序中最后肯定是根结点
root_index = inorder.index(root.val)
root.left = self.buildTree(inorder[:root_index],
postorder[:root_index]) #左闭右开
root.right = self.buildTree(inorder[root_index + 1:],
postorder[root_index:-1])
return root
if not root:
return 0
return max(self.maxDepth1(root.left), self.maxDepth1(root.right)) + 1
def maxDepth2(self, root):
'''
BFS
'''
if not root:
return 0
que = []
que.append((root, 1))
while que:
cur, depth = que.pop(0)
if cur.left != None: que.append((cur.left, depth + 1))
if cur.right != None: que.append((cur.right, depth + 1))
return depth
def maxDepth(self, root):
return self.maxDepth2(root)
if __name__ == '__main__':
s = Solution()
root = TreeNode(3)
root.left = TreeNode(9)
root.right = TreeNode(20)
root.right.left = TreeNode(15)
root.right.right = TreeNode(7)
print(s.maxDepth(root))
res = []
self.getPath(root, sum, [], res)
return res
def getPath(self, root, sums, tmp, res):
tmp.append(root.val)
if (root.left == None) and (root.right == None):
if sum(tmp) == sums:
res.append(tmp)
return
if root.left != None:
self.getPath(root.left, sums, tmp[:], res) # 传入的tmp是快照
if root.right != None:
self.getPath(root.right, sums, tmp[:], res)
if __name__ == '__main__':
s = Solution()
root = TreeNode(5)
root.left = TreeNode(4)
root.left.left = TreeNode(11)
root.left.left.left = TreeNode(7)
root.left.left.right = TreeNode(2)
root.right = TreeNode(8)
root.right.left = TreeNode(13)
root.right.right = TreeNode(4)
root.right.right.left = TreeNode(5)
root.right.right.right = TreeNode(1)
print(s.pathSum(root, 22))
:rtype: List[int]
"""
res = []
if not root:
return res
stack = []
stack.append(root)
while stack != []:
tmp = stack[-1]
res.append(tmp.val) # 取根节点的值
stack.pop()
if tmp.right:
stack.append(tmp.right) # 先压右节点
if tmp.left:
stack.append(tmp.left) # 再压左节点
return res
def preorderTraversal(self, root):
return self.preorderTraversal1(root)
if __name__ == '__main__':
s = Solution()
root = TreeNode(3)
root.left = TreeNode(1)
root.right = TreeNode(2)
print(s.preorderTraversal(root))
# stack = []
# stack.append('3')
# tmp = stack[0]
# print(tmp)
return 0
if take:
if root.left not in storage_0:
storage_0[root.left] = helper(root.left, 0)
if root.right not in storage_0:
storage_0[root.right] = helper(root.right, 0)
return root.val + storage_0[root.left] + storage_0[root.right]
else:
if root.left not in storage_0:
storage_0[root.left] = helper(root.left, 0)
if root.right not in storage_0:
storage_0[root.right] = helper(root.right, 0)
if root.left not in storage_1:
storage_1[root.left] = helper(root.left, 1)
if root.right not in storage_1:
storage_1[root.right] = helper(root.right, 1)
return max(storage_0[root.left], storage_1[root.left]) + max(
storage_0[root.right], storage_1[root.right])
return max(helper(root, 0), helper(root, 1))
if __name__ == '__main__':
s = Solution()
root = TreeNode(3)
root.left = TreeNode(4)
root.left.left = TreeNode(1)
root.left.right = TreeNode(3)
root.right = TreeNode(5)
root.right.right = TreeNode(1)
print(s.rob(root))
res = []
if not root:
return res
map = {}
def helper(root):
if not root:
return 0
tmp = root.val + helper(root.left) + helper(root.right)
map[tmp] = map.get(tmp, 0) + 1
return tmp
helper(root)
max_sum = 0
for k, v in map.items():
if v > max_sum:
max_sum = v
res.clear() # or res[:] = []，python3.3后才有.clear()
res.append(k)
elif v == max_sum:
res.append(k)
return res
if __name__ == '__main__':
root = TreeNode(5)
root.left = TreeNode(2)
root.right = TreeNode(-5)
s = Solution()
print(s.findFrequentTreeSum(root))
if not res:
res = self.HasSubtree(pRoot1.left, pRoot2) # A树的左节点中有没有
if not res:
res = self.HasSubtree(pRoot1.right, pRoot2) # A树的右节点中有没有
return res
def isSubtree(self, root1, root2):
if not root2:
return True
if not root1:
return False
if root1.val == root2.val:
return self.isSubtree(root1.left, root2.left) and self.isSubtree(root1.right, root2.right)
else:
return False
if __name__ == '__main__':
s = Solution()
a = TreeNode(8)
a.left = TreeNode(8)
a.left.left = TreeNode(9)
a.left.left.left = TreeNode(9)
a.left.right = TreeNode(2)
a.right = TreeNode(7)
b = TreeNode(8)
b.left = TreeNode(9)
b.right = TreeNode(2)
print(s.HasSubtree(a, b))
tmp = root.left
root.left = root.right
root.right = tmp
self.Mirror(root.left)
self.Mirror(root.right)
def OutputTreeFront(root):
"""
先序遍历：根结点 ---> 左子树 ---> 右子树
"""
if root == None:
return
print(root.val)
OutputTreeFront(root.left)
OutputTreeFront(root.right)
if __name__ == '__main__':
s = Solution()
root = TreeNode(8)
root.left = TreeNode(6)
root.right = TreeNode(10)
# root.left.left = TreeNode(5)
root.left.right = TreeNode(7)
root.right.left = TreeNode(9)
root.right.right = TreeNode(11)
s.Mirror(root)
OutputTreeFront(root)
从上往下打印二叉树
从上往下打印出二叉树的每个节点，同层节点从左至右打印。
'''
from tool import TreeNode
class Solution:
# 返回从上到下每个节点值列表，例：[1,2,3]
def PrintFromTopToBottom(self, root):
if not root:
return []
res = []
que = [root]
while que:
cur = que.pop(0)
res.append(cur.val)
if cur.left: que.append(cur.left)
if cur.right: que.append(cur.right)
return res
if __name__ == '__main__':
s = Solution()
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.right.left = TreeNode(6)
root.right.right = TreeNode(7)
print(s.PrintFromTopToBottom(root))