Algorithm (1)-Binary Tree

1. Concept

1. Node

• Parent node
• Child node
• Sibling nodes: nodes of the same parent node
• Root node: a node without a parent node
• Leaf nodes: nodes without byte points

2 depth level

• Height: count from bottom to top
• Depth: Counting from top to bottom
• Floor:

3 Full Binary Tree Complete Binary Tree

Full binary tree:

• The leaf nodes are all at the bottom;
• Except for the leaf nodes, the rest of the nodes all contain two left and right nodes.
  
  Complete binary tree:
• Except for the last layer, the number of nodes in other layers must reach the maximum
• The last layer of leaf nodes are arranged to the left
  

4 Traversal of Binary Tree

Named according to the order of the root nodes

Pre-order traversal: root left and right
Middle-order traversal: left root right
Post-order traversal: left and right root

Second, the code implementation

Array-based sequential storage method

Application: complete binary tree,
method:
suppose that the root node is subscript i in the array, and i=1
the left child node of the root node: i * 2
the right child node of the root node: i * 2+1

Core code:
Prerequisite: The array data stores the data of a complete binary tree

///<summary>
///
///<param name="index"></param>
///</summary>
private void preOrder(int index)
{
    
    
	if(index>=data.Count||data[index].IsNullOrEmpty()){
    
    
		return ;
	}
	int num=index;
	Console.write(data[index]+" ");
	var leftNum=num*2;
	var rightNum=num*2+1;
	preOrder(leftNum);
	preOrder(rightNum);
}

Based on linked list