根据前序序列和中序序列,重建一颗树(PHP递归实现)
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2022-05-11 18:38:55
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class TreeNode{ public $data; public $lchild = null; public $rchild = null; public function __construct($data='',$lchild=null,$rchild=null){ $this->data = $data; $this->lchild = $lchild; $this->rchild = $rchild; }}
//根据前序和中序,重建一颗树 //$pre 前序遍历的数组 //$mid 中序遍历的数组 function buildTree($pre,$mid){ $cnt = count($mid); if($cnt0) $node->lchild = buildTree(array_slice($pre,1,$lenL),array_slice($mid,0,$lenL)); if($lenR>0) $node->rchild = buildTree(array_slice($pre,$lenL+1,$lenR),array_slice($mid,$lenL+1,$lenR)); return $node; } $mid = array(4,7,2,1,5,3,8,6); $pre = array(1,2,4,7,3,5,6,8); $node = buildTree($pre,$mid); echo ''; var_dump($node); echo '';
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