1 <?php 2 #树节点 3 class Node { 4 public $lc = null; #左孩子 5 public $rc = null; #右孩子 6 public $val; 7 8 public function __construct($val) { 9 $this->val = $val; 10 } 11 } 12 13 #先序遍历 14 function preTraverse(Node $root) { 15 echo $root->val . " "; 16 if($root->lc != null) preTraverse($root->lc); 17 if($root->rc != null) preTraverse($root->rc); 18 } 19 20 #中序遍历 21 function inTraverse(Node $root) { 22 if($root->lc != null) inTraverse($root->lc); 23 echo $root->val . " "; 24 if($root->rc != null) inTraverse($root->rc); 25 } 26 27 #后序遍历 28 function postTraverse(Node $root) { 29 if($root->lc != null) postTraverse($root->lc); 30 if($root->rc != null) postTraverse($root->rc); 31 echo $root->val . " "; 32 } 33 34 $root = new Node(3); 35 $node1 = new Node(2); 36 $node2 = new Node(1); 37 $node3 = new Node(6); 38 $node4 = new Node(5); 39 $node5 = new Node(7); 40 41 $root->lc = $node1; 42 $root->rc = $node3; 43 $node1->lc = $node2; 44 $node3->lc = $node4; 45 $node3->rc = $node5; 46 47 preTraverse($root); 48 echo "<br>"; 49 inTraverse($root); 50 echo "<br>"; 51 postTraverse($root); 52 ?>
输出
3 2 1 6 5 7
1 2 3 5 6 7
1 2 5 7 6 3
