Analyze how to convert an array into a binary tree structure in php

In PHP, converting an array into a binary tree is a very practical skill, especially when processing data. This article explains how to implement this process in PHP.

1. What is a binary tree?

Binary tree is a tree data structure, each node in the tree has at most two child nodes. A tree is a hierarchical data structure. Each node in the tree can have zero or more child nodes. The number of levels in the tree is calculated starting from the root node. A binary tree is a special kind of tree, each node has no more than two child nodes, and the positions of the left and right subtrees are fixed.

Binary trees can access their nodes according to different traversal methods. Commonly used ones include pre-order traversal, in-order traversal and post-order traversal. Preorder traversal means that the parent node is visited before the left and right child nodes, inorder traversal means that the parent node is visited between the left and right child nodes, and postorder traversal means that the parent node is visited after the left and right child nodes.

2. Convert an array into a binary tree

In PHP, to convert an array into a binary tree, you need to follow the following steps:

1) Get the length of the array, That is the number of nodes.

2) Construct a binary tree according to the array index method, first obtain the root node and assign its value to the root node.

3) Traverse the array recursively, create a new node each time, and assign the data value of the node to the current node. Then continue to recurse the left subtree and right subtree until the array is traversed.

The following is the code implementation:

class Node {

public $value; public $left; public $right; public function __construct($value) { $this->value = $value; $this->left = NULL; $this->right = NULL; }
 
}
 
function array_to_tree($array, $i) {
 
if (isset($array[$i])) { $node = new Node($array[$i]); $node->left = array_to_tree($array, 2 * $i + 1); $node->right = array_to_tree($array, 2 * $i + 2); return $node; } return NULL;
        

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}

$array = array(1, 2, 3, 4, 5, 6, 7);
$root = array_to_tree($array, 0 );

?>

3. Conclusion

Through this article, we have learned about the process of converting an array into a binary tree in PHP, including how to build nodes and recursive left and right subtrees. Mastering this skill will help us operate more efficiently when processing application data.

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