1 <?php 2 #生成二叉树镜像(交换树的所有左右节点) 3 4 class Node { 5 public $data = null; 6 public $parent = null; 7 public $left = null; 8 public $right = null; 9 } 10 11 #递归方法 12 function mirror_recursive($root) { 13 if ($root === null) { 14 return; 15 } 16 17 mirror_recursive($root->left); 18 mirror_recursive($root->right); 19 $temp = $root->left; 20 $root->left = $root->right; 21 $root->right = $temp; 22 } 23 24 #非递归方法,用一个栈或队列都可以,类似于深度优先和广度优先遍历 25 function mirror_norec($root) { 26 $queue = array(); 27 array_unshift($queue, $root); 28 29 while (!empty($queue)) { 30 $cnode = array_pop($queue); 31 if ($cnode->left !== null) array_unshift($queue, $cnode->left); 32 if ($cnode->right !== null) array_unshift($queue, $cnode->right); 33 $temp = $cnode->left; 34 $cnode->left = $cnode->right; 35 $cnode->right = $temp; 36 } 37 } 38 39 #中序遍历 40 function inorder_traverse($root) { 41 if ($root->left !== null) inorder_traverse($root->left); 42 echo $root->data . " "; 43 if ($root->right !== null) inorder_traverse($root->right); 44 } 45 46 $root = new Node(); 47 $n1 = new Node(); 48 $n2 = new Node(); 49 $n11 = new Node(); 50 $n12 = new Node(); 51 $n13 = new Node(); 52 $n14 = new Node(); 53 $n15 = new Node(); 54 $n21 = new Node(); 55 56 $root->data = 0; 57 $n1->data = 1; 58 $n2->data = 2; 59 $n11->data = 11; 60 $n12->data = 12; 61 $n13->data = 13; 62 $n14->data = 14; 63 $n15->data = 15; 64 $n21->data = 21; 65 66 $root->left = $n1; 67 $root->right = $n2; 68 $n1->left = $n11; 69 $n1->right = $n12; 70 $n11->left = $n13; 71 $n12->right = $n14; 72 $n13->left = $n15; 73 $n2->right = $n21; 74 75 inorder_traverse($root); 76 echo "<br>"; 77 mirror_recursive($root); 78 inorder_traverse($root); 79 echo "<br>"; 80 mirror_norec($root); 81 inorder_traverse($root); 82 ?>
15 13 11 1 12 14 0 2 21
21 2 0 14 12 1 11 13 15
15 13 11 1 12 14 0 2 21
