def sortedArrayToBST(arr):
if not arr:
return None
mid = len(arr) // 2
root = TreeNode(arr[mid])
root.left = sortedArrayToBST(arr[:mid])
root.right = sortedArrayToBST(arr[mid + 1:])
return root
def sorted_array_to_bst(array):
if len(array) == 0:
return None
elif len(array) == 1:
return TreeNode(array[0])
else:
mid = int(len(array) / 2)
root = TreeNode(array[mid])
root.left = sorted_array_to_bst(array[:mid])
root.right = sorted_array_to_bst(array[mid + 1:])
return root
def insert(self, root, value):
if root == None:
return
else:
if root.val > value:
if root.left == None:
root.left = TreeNode(value)
else:
self.insert(root.left, value)
else:
if root.right == None:
root.right = TreeNode(value)
else:
self.insert(root.right, value)
def construct(inorder, preorder):
if len(inorder) == 0 or len(preorder) == 0:
return None
else:
root = preorder[0]
index = inorder.index(root)
left_inorder = inorder[:index]
right_inorder = inorder[index + 1:]
left_preorder = preorder[1:1 + len(left_inorder)]
right_preorder = preorder[1 + len(left_inorder):]
root = TreeNode(root)
root.left = construct(left_inorder, left_preorder)
root.right = construct(right_inorder, right_preorder)
return root
def min_tree(arr):
# base case
if len(arr) is 0:
return None
# make node from middle of array
mid = len(arr) / 2
node = TreeNode(arr[mid])
# recursively make node from each middle of each half of each array
node.left = min_tree(arr[:mid])
node.right = min_tree(arr[mid + 1:]) # +1 to not include current mid
# returns root
return node
def search(queue, method, initial_game):
root = TreeNode(initial_game, None, None, 0, 0, 0)
if method == 'astar' or method == 'best':
queue.put((0, root))
else:
queue.put(root)
visited_states = set()
start = time.time()
while (not queue.empty()) and (time.time() - start <= 300):
if method == 'astar' or method == 'best':
curr_f, current = queue.get()
else:
current = queue.get()
if current.is_goal():
return current
# If the state of the game has already been visited, then continue
if str(current.game) in visited_states:
continue
current.find_children(method)
visited_states.add(str(current.game))
for child in current.children:
if method == 'depth' or method == 'breadth':
queue.put(child)
elif method == 'astar' or method == 'best':
queue.put((child.f, child))
print(child.game)
print("===============================")
return None
def monte_carlo_tree_search(board, pre_pos):
root = TreeNode(board=board, pre_pos=pre_pos) # 根结点，根结点无父亲
for i in range(
mcts_times
): # 相当于(while resources_left(time, computational power):)即资源限制
leaf = traverse(root) # 选择和扩展，leaf = unvisited node（遍历根结点）
simulation_result = rollout(leaf) # 模拟
backpropagate(leaf, simulation_result) # 反向传播
return best_child(root).pre_pos
def insert(tree, dataval):
if tree.root is None:
tree.root = TreeNode(dataval)
else:
pointer1 = tree.root
while pointer1 is not None:
if pointer1.dataval > dataval:
if pointer1.leftchild is None:
pointer1.leftchild = TreeNode(dataval)
return
else:
pointer1 = pointer1.leftchild
elif pointer1.dataval < dataval:
if pointer1.rightchild is None:
pointer1.rightchild = TreeNode(dataval)
return
else:
pointer1 = pointer1.rightchild
else:
pointer1.duplicates += 1
return
def insert(self, key: int):
if self.root is None:
self.root = TreeNode(key)
return
parent = self.root
if parent.key == key:
raise KeyError("Repeated key")
child = parent.left if key < parent.key else parent.right
while child is not None:
parent = child
if parent.key == key:
raise KeyError("Repeated key")
child = child.left if key < child.key else child.right
newNode = TreeNode(key)
newNode.parent = parent
if newNode.key < parent.key:
parent.left = newNode
else:
parent.right = newNode
def tree_insert(self, z: TreeNode):
y = None
x = self.head
while x:
y = x
x = x.left if z.value < x.value else x.right
z.parent = y
if not y:
self.head = z
elif z.value < y.value:
y.left = z
else:
y.right = z
def transplant(self, u: TreeNode, v: TreeNode):
"""
NB: transplant() doesn't attempt to update v.left and v.right
doing so, or not doing so, is the responsibility of transplant()'s caller
:param u:
:param v:
:return:
"""
if not u.parent:
self.head = v
elif u == u.parent.left:
u.parent.left = v
else:
u.parent.right = v
if not v:
v.parent = u.parent
# rType- TreeNode
# input - TreeNode
def successor(root):
if root.right:
return minValue(root.right)
parent = root.parent
while parent:
if root != parent.right:
break
root = parent
parent = parent.parent
return parent
if __name__ == "__main__":
twenty = TreeNode(20)
eight = TreeNode(20)
four = TreeNode(4)
twelve = TreeNode(12)
ten = TreeNode(10)
fourteen = TreeNode(14)
twentytwo = TreeNode(22)
# setting Parents
eight.parent = twenty
four.parent = eight
twelve.parent = eight
ten.parent = twelve
fourteen.parent = twelve
twentytwo.parent = twenty
# left right
twenty.right = twentytwo
def addNode(self, label):
if label not in self.nodes:
self.nodes[label] = TreeNode(label)
return self.nodes[label]
Validate BST: Implement a function to check if a binary tree is a binary search tree.
'''
from Node import TreeNode, preOrderTraversal, postOrderTraversal, inOrderTraversal
# recent keeps track of the last value compared
def validBST(root, recent):
if not root:
return True
if not (validBST(root.left, recent)):
return False
if recent is not None and root.value <= recent:
return False
recent = root.value
if not (validBST(root.right, recent)):
return False
return True
if __name__ == "__main__":
one = TreeNode(1)
two = TreeNode(2)
three = TreeNode(3)
four = TreeNode(4)
five = TreeNode(5)
six = TreeNode(6)
seven = TreeNode(7)
eight = TreeNode(8)
print(validBST(one, None))
# left & right heights
left_height = root.height(root.left)
right_height = root.height(root.right)
# get positive value of difference in height
height_difference = abs(left_height - right_height)
# check height requirement satisfied
if height_difference <= 1:
# ... recursively
if check_balanced(root.left) is True and check_balanced(
root.right) is True:
return True
# if we reach here means tree is not
# height-balanced tree
return False
if __name__ == "__main__":
bal_root = min_tree([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12])
print(check_balanced(bal_root))
unbal_root = TreeNode(5)
unbal_root.left = TreeNode(4)
unbal_root.left.left = TreeNode(3)
unbal_root.left.left.left = TreeNode(2)
unbal_root.left.left.left.left = TreeNode(1)
unbal_root.right = TreeNode(6)
print(check_balanced(unbal_root))
return checkSubtree(r1.left, r2) or checkSubtree(r1.right, r2)
def sameTree(r1, r2):
if not r1 and not r2:
return True
elif not r1 or not r2:
return False
elif r1.value != r2.value:
return False
else:
return sameTree(r1.left, r2.left) and sameTree(r1.right, r2.right)
if __name__ == "__main__":
one = TreeNode(1)
two = TreeNode(2)
three = TreeNode(3)
four = TreeNode(4)
five = TreeNode(5)
six = TreeNode(6)
seven = TreeNode(7)
eight = TreeNode(8)
one.left = two
one.right = three
two.left = four
two.right = five
three.left = six
three.right = seven
r1 = one
newOne = TreeNode(2)
return result
prefix = []
prefix.append(node.value)
leftSeq = self.allSequences(node.left)
rightSeq = self.allSequences(node.right)
for first in leftSeq:
for second in rightSeq:
weaved = []
self.weavedLists(first, second, weaved, prefix)
for item in weaved:
result.append(item)
return result
if __name__ == "__main__":
fifty = TreeNode(50)
twenty = TreeNode(20)
sixty = TreeNode(60)
ten = TreeNode(10)
twentyFive = TreeNode(25)
seventy = TreeNode(70)
five = TreeNode(5)
fifteen = TreeNode(15)
sixtyFive = TreeNode(65)
eighty = TreeNode(80)
fifty.left = twenty
fifty.right = sixty
twenty.left = ten
twenty.right = twentyFive
sixty.right = seventy
ten.left = five
def append(self, value):
newNode = TreeNode(value)
self.placeNode(newNode, self.root)
def __init__(self, value):
self.setRoot(TreeNode(value))
from Node import TreeNode def preorder_traversal(n): if n == None: return else: print(n.val, end=" ") preorder_traversal(n.left) preorder_traversal(n.right) def preorder_traversal_iterative(n): stack = [n] while(len(stack) != 0): node = stack.pop() if node.is_visited: print(node.val, end=" ") else: if node.right != None: stack.append(node.right) if node.left != None: stack.append(node.left) node.is_visited = True stack.append(node) n = TreeNode.get_sample() preorder_traversal(n) print() preorder_traversal_iterative(n)
childNode = parentNode.left
else:
childNode = parentNode.right
stack.pop()
stack.append((parentNode, parentState - 1))
if childNode:
stack.append((childNode, bothPending))
else:
if oneNodeFound and len(stack) - 1 == fcaIndex:
fcaIndex -= 1
stack.pop()
return None
if __name__ == "__main__":
one = TreeNode(1)
two = TreeNode(2)
three = TreeNode(3)
four = TreeNode(4)
five = TreeNode(5)
six = TreeNode(6)
seven = TreeNode(7)
eight = TreeNode(8)
nine = TreeNode(9)
one.left = two
one.right = three
two.left = four
two.right = five
three.left = six
three.right = seven
four.left = eight
def isValidBST(root, max_val, min_val):
if root == None:
return True
else:
if root.val > max_val or root.val < min_val:
return False
else:
if (root.left != None and root.val < root.left.val) or (
root.right != None and root.val > root.right.val):
return False
else:
return isValidBST(root.left, root.val, min_val) and isValidBST(
root.right, max_val, root.val)
head = TreeNode.get_sample()
print(isValidBST(head, sys.maxsize, -sys.maxsize - 1))
n1 = TreeNode(1)
n2 = TreeNode(2)
n3 = TreeNode(3)
n4 = TreeNode(4)
n5 = TreeNode(5)
n6 = TreeNode(6)
n7 = TreeNode(7)
n4.left = n2
n4.right = n5
n2.right = n3
n2.left = n1
n5.right = n6
