PHP ClassObject In depth analysis of PHP self sorting binary trees

  • 2020-06-19 10:03:04
  • OfStack

Apply a little more sorting logic between nodes, and a two-tree provides excellent organization. For each node, the elements that satisfy all the specific conditions are located on the left node and its children. When inserting a new element, we need to start at the first node of the tree (the root node), determine which side of the node it belongs to, and then find the appropriate position along this side. Similarly, when reading data, we only need to use the sequential traversal method to traverse the two-tree.

<?php
ob_start();
// Here we need to include the binary tree class
Class Binary_Tree_Node() {
   // You can find the details at
}
ob_end_clean();
// Define a class to implement self sorting binary tree
class Sorting_Tree {
    // Define the variable to hold our tree:
    public $tree;
    // We need a method that will allow for inserts that automatically place
    // themselves in the proper order in the tree
    public function insert($val) {
        // Handle the first case:
        if (!(isset($this->tree))) {
            $this->tree = new Binary_Tree_Node($val);
        } else {
            // In all other cases:
            // Start a pointer that looks at the current tree top:
            $pointer = $this->tree;
            // Iteratively search the tree for the right place:
            for(;;) {
                // If this value is less than, or equal to the current data:
                if ($val <= $pointer->data) {
                    // We are looking to the left ... If the child exists:
                    if ($pointer->left) {
                        // Traverse deeper:
                        $pointer = $pointer->left;
                    } else {
                        // Found the new spot: insert the new element here:
                        $pointer->left = new Binary_Tree_Node($val);
                        break;
                    }
                } else {
                    // We are looking to the right ... If the child exists:
                    if ($pointer->right) {
                        // Traverse deeper:
                        $pointer = $pointer->right;
                    } else {
                        // Found the new spot: insert the new element here:
                        $pointer->right = new Binary_Tree_Node($val);
                        break;
                    }
                }
            }
        }
    }

    // Now create a method to return the sorted values of this tree.
    // All it entails is using the in-order traversal, which will now
    // give us the proper sorted order.
    public function returnSorted() {
        return $this->tree->traverseInorder();
    }
}
// Declare a new sorting tree:
$sort_as_you_go = new Sorting_Tree();
// Let's randomly create 20 numbers, inserting them as we go:
for ($i = 0; $i < 20; $i++) {
    $sort_as_you_go->insert(rand(1,100));
}
// Now echo the tree out, using in-order traversal, and it will be sorted:
// Example: 1, 2, 11, 18, 22, 26, 32, 32, 34, 43, 46, 47, 47, 53, 60, 71,
//   75, 84, 86, 90
echo '<p>', implode(', ', $sort_as_you_go->returnSorted()), '</p>';
?>


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