PHP Class&Object -- 解析PHP实现二叉树
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PHP Class&Object -- 解析PHP实现二叉树，
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二叉树及其变体是数据结构家族里的重要组成部分。最为链表的一种变体，二叉树最适合处理需要一特定次序快速组织和检索的数据。
<div class="codetitle"><a style="CURSOR: pointer" data="84330" class="copybut" id="copybut84330" onclick="doCopy('code84330')"> 代码如下:
<div class="codebody" id="code84330">
<?
PHP// Define a class to implement a binary tree
class Binary_Tree_Node {
// Define the variable to hold our data:
public $data;
// And a variable to hold the left and right objects:
public $left;
public $right; // A constructor method that allows for data to be passed in
public function __construct($d = NULL) {
$this->data = $d;
} // Traverse the tree,left to right,in pre-order,returning an array
// Preorder means that each node's value preceeds its children.
public function traversePreorder() {
// Prep some variables.
$l = array();
$r = array();
// Read in the left and right children appropriately traversed:
if ($this->left) { $l = $this->left->traversePreorder(); }
if ($this->right) { $r = $this->right->traversePreorder(); } // Return a merged array of the current value,left,and right:
return array_merge(array($this->data),$l,$r);
}
// Traverse the tree,in postorder,returning an array
// Postorder means that each node's value follows its children.
public function traversePostorder() {
// Prep some variables.
$l = array();
$r = array();
// Read in the left and right children appropriately traversed:
if ($this->left) { $l = $this->left->traversePostorder(); }
if ($this->right) { $r = $this->right->traversePostorder(); } // Return a merged array of the current value,and right:
return array_merge($l,$r,array($this->data));
}
// Traverse the tree,in-order,returning an array.
// In-order means that values are ordered as left children,then the
// node value,then the right children.
public function traverseInorder() {
// Prep some variables.
$l = array();
$r = array();
// Read in the left and right children appropriately traversed:
if ($this->left) { $l = $this->left->traverseInorder(); }
if ($this->right) { $r = $this->right->traverseInorder(); } // Return a merged array of the current value,array($this->data),$r);
}
}
// Let's create a binary tree that will equal the following: 3
// / /
// h 9
// / /
// Create the tree: 6 a
$tree = new Binary_Tree_Node(3);
$tree->left = new Binary_Tree_Node('h');
$tree->right = new Binary_Tree_Node(9);
$tree->right->left = new Binary_Tree_Node(6);
$tree->right->right = new Binary_Tree_Node('a');
// Now traverse this tree in all possible orders and display the results:
// Pre-order: 3,h,9,6,a
echo '
',implode(',',$tree->traversePreorder()),'
';
// Post-order: h,a,3
echo '
',$tree->traversePostorder()),'
';
// In-order: h,3,$tree->traverseInorder()),'';
?>
