def construct_helper(pre_order, in_order, pre_start, pre_end, in_start,
in_end):
if pre_start > pre_end:
return
index = -1
for (i, num) in enumerate(in_order):
if num == pre_order[pre_start]:
index = i
break
if index == -1:
raise RuntimeError(u"错误的输入")
root = TreeNode(pre_order[index])
left_length = index - in_start
root.left = construct_helper(pre_order, in_order, pre_start + 1,
pre_start + left_length, in_start, index - 1)
root.right = construct_helper(pre_order, in_order,
pre_start + left_length + 1, pre_end,
index + 1, in_end)
return root
def helper(root, n, val, nodes):
val += root.val
nodes.append(root)
if not root.left and not root.right:
if val == n:
for node in nodes:
print node.val,
print "\n"
nodes.pop()
return
if root.left:
helper(root.left, n, val, nodes)
if root.right:
helper(root.right, n, val, nodes)
nodes.pop()
if __name__ == '__main__':
node1 = TreeNode(10)
node2 = TreeNode(5)
node3 = TreeNode(12)
node4 = TreeNode(4)
node5 = TreeNode(7)
node6 = TreeNode(6)
node7 = TreeNode(7)
node1.left = node2
node1.right = node3
node2.left = node4
node2.right = node5
print_path_of_n(node1, 22)
right = get_depth_of_tree(root.right)
return left + 1 if left > right else right + 1
def is_balanced_tree(root):
if not root:
return True, 0
left, left_depth = is_balanced_tree(root.left)
right, right_depth = is_balanced_tree(root.right)
return left and right and abs(
left_depth - right_depth) <= 1, \
left_depth + 1 if left_depth > right_depth else right_depth + 1
if __name__ == '__main__':
node1 = TreeNode(1)
node2 = TreeNode(2)
node3 = TreeNode(3)
node4 = TreeNode(4)
node5 = TreeNode(5)
node6 = TreeNode(6)
node7 = TreeNode(7)
node1.left = node2
node1.right = node3
node2.left = node4
node2.right = node5
node3.left = node6
node3.right = node7
print get_depth_of_tree(node1)
print is_balanced_tree(node1)
def helper(root1, root2):
if not root2:
return True
if not root1 or root1.val != root2.val:
return False
return helper(root1.left, root2.left) and helper(root1.right, root2.right)
if __name__ == '__main__':
node1 = TreeNode(1)
node2 = TreeNode(2)
node3 = TreeNode(3)
node4 = TreeNode(4)
node5 = TreeNode(5)
node6 = TreeNode(6)
node7 = TreeNode(7)
node1.left = node2
node1.right = node3
node2.left = node4
node2.right = node5
node3.left = node6
node3.right = node7
node8 = TreeNode(2)
node9 = TreeNode(4)
node10 = TreeNode(5)
node8.left = node9
node8.right = node10
print is_substructure_of_tree(node1, node8)