def bst_2(cls, negtive=True):
if negtive:
root = TreeNode(0)
root.right = TreeNode(-1)
else:
root = TreeNode(1)
root.right = TreeNode(3)
root.right.left = TreeNode(2)
return root
def convert(left, right):
if left > right: return None
mid = (left + right) // 2
node = TreeNode(nums[mid])
node.left = convert(left, mid - 1)
node.right = convert(mid + 1, right)
return node
def bst_230(cls):
"""
3
/ \
1 4
\
2
"""
root = TreeNode(3)
root.left = TreeNode(1)
root.right = TreeNode(4)
root.left.right = TreeNode(2)
return root
def bst_1(cls, negtive=True):
"""
2
/ \
1 3
"""
if negtive:
root = TreeNode(2)
root.left = TreeNode(1)
root.right = TreeNode(3)
else:
root = TreeNode(1)
root.left = TreeNode(1)
return root
def bst_501(cls, extend=False):
""" 4、3 都可切成 5
4
/ \
2 6
/ \ / \
1 3 5 6
"""
if not extend:
root = TreeNode(1)
root.right = TreeNode(2)
root.right.left = TreeNode(2)
return root
else:
root = TreeNode(5)
root.left, root.right = TreeNode(2), TreeNode(6)
root.left.left, root.left.right = TreeNode(1), TreeNode(3)
root.right.left, root.right.right = TreeNode(5), TreeNode(6)
return root