Total number of branches = number of summary points-1
Number of leaf nodes = number of double branch nodes + 1
Preface Traversal: Root left and right
Mid-order traversal: left root right
Post-order traversal: left and right root
Note: Knowing that pre-order and post-order cannot uniquely determine a binary tree
Binary sort tree definition:
1 ) If its left subtree is not empty, then the values of all keywords on the left subtree are less than the value of the root keyword;
2) If its right subtree is not empty, then the right subtree The value of all the keywords in the tree is greater than the value of the root keyword;
3) The left and right subtrees are each a binary sort tree.
The definition of balanced binary tree:
Balanced binary tree, also known as AVL tree, is a special binary sort tree. The left and right subtrees are both balanced binary trees, and the absolute value of the difference between the height of the left and right subtrees does not exceed 1.