if root1 is None and root2 is None:
return True
# if root1.val == root2.val:
# return dfs(root1.left, root2.left) and \
# dfs(root1.right, root2.right)
# else:
# return False
# TOREAD: better wrote
if root1 is not None and root2 is not None:
return (root1.val == root2.val) and \
dfs(root1.left, root2.left) and \
dfs(root1.right, root2.right)
else:
return False
return dfs(tree1, tree2)
if __name__ == '__main__':
tree1 = tree2 = build_tree([100, 50, 200, '#', 25, 125, 350])
print_tree(tree1)
assert True == check_identical_trees(tree1, tree2)
tree1 = build_tree([100, 50, 200, '#', 25, 125, 350])
tree2 = build_tree([100, 50, 200, '#', 25, 125, 250])
print_tree(tree1)
print_tree(tree2)
assert False == check_identical_trees(tree1, tree2)
def iter_inorder(tree):
# visit == print
# left, root, right
root = tree
stack = []
nodes = []
while len(stack) or root is not None:
if root is not None:
stack.append(root)
root = root.left
continue
# TOREAD: process it and git rid of it at last
nodes.append(stack[-1].val)
root = stack[-1].right
stack.pop()
print
print nodes
if __name__ == '__main__':
tree = build_tree([100, 50, 200, 25, 75, 125, 350])
print_tree(tree)
order = [25, 50, 75, 100, 125, 200, 350]
iter_inorder(tree)
from helper import build_tree
from helper import print_tree
def mirror_tree(root):
# post order swap
def swap_node(root):
if not root:
return
swap_node(root.left)
swap_node(root.right)
root.left, root.right = root.right, root.left
return swap_node(root)
if __name__ == '__main__':
tree = build_tree([20, 50, 200, 25, 75, '#', 300])
print_tree(tree)
print
mirror_tree(tree)
print_tree(tree)
from helper import build_tree
from helper import print_tree
def delete_zero_sum_in(tree):
def sub_sum_tree(root):
if root is None:
return 0
# TOREAD: post order search
left_sum = sub_sum_tree(root.left)
right_sum = sub_sum_tree(root.right)
# TOREAD: just some process different than tree sum
if left_sum == 0:
root.left = None
elif right_sum == 0:
root.right = None
return root.val + left_sum + right_sum
return sub_sum_tree(tree)
if __name__ == '__main__':
tree = build_tree([7, 5, 6, -3, -2, '#', '#'])
print_tree(tree)
delete_zero_sum_in(tree)
print_tree(tree)