php PHP二叉树递归算法
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PHP Binary Tree Recursion Algorithm
提问by jkushner
I want to create a PHP recursive program using a Binary Tree and Recursion.
我想使用二叉树和递归创建一个 PHP 递归程序。
I want to print the binary tree level by level using recursion. I want to recurse through the tree, push the node into a hashmap that has the level as the reference point.
我想使用递归逐级打印二叉树。我想通过树递归，将节点推送到以级别为参考点的哈希图中。
Here's what I have so far:
这是我到目前为止所拥有的：
$binary_tree = array(array(1 => array(2 => array(4,5),4=>array(5,6))));
1
|
------------------
| |
2 4
| |
---------- ----------
| | | |
4 5 5 6
And the end result should look like this:
最终结果应该是这样的：
$data[0] = array(1);
$data[1] = array(2,4);
$data[2] = array(4,5,5,6);
I can easily loop through the array and print out the numbers, which are corresponding to the level(the array index).
我可以轻松地遍历数组并打印出与级别（数组索引）相对应的数字。
Here's the function, which is wrong, but my first shot:
这是函数，这是错误的，但我的第一个镜头：
function recurse_tree($data,$level=0){
$final = array();
$tmp = array()
// first check if data is array
if(is_array($data)){
// loop through data
foreach($data as $elm){
// push data to the tmp array
$tmp[] = recurse_tree($elm,$level+1);
}
// not an array
} else {
// push data to the final array. can we push to the tmp array.
array_push($final[level],$elm);
}
// merge final and tmp array and return
return ($final + $tmp);
}
I am not too experienced with recursion nor problem solving, so I wrote out the steps below which are occurring. The problem I have here now is that on step 9 I an unsure how to handle the keys 2 and 4, and then finally to handle the root node, key 1. Also, when I get to steps 5-8, im at level 4, which is correct, however according to the tree, its level 2.
我对递归和解决问题的经验都不是很丰富，所以我写出了下面正在发生的步骤。我现在遇到的问题是，在第 9 步我不确定如何处理键 2 和 4，然后最后处理根节点，键 1。此外，当我到达第 5-8 步时，我处于第 4 级，这是正确的，但是根据树，它的级别为 2。
$flattened_tree = recurse_tree($data);
// STEPS:
1./ called recurse_tree
data: array(array(1 => array(2 => array(4,5),4=>array(5,6))));
level: 0
final: array();
tmp: array();
2./ called recurse_tree:
data: array(1 => array(2 => array(4,5),4=>array(5,6)));
level: 1
final: array();
tmp: array();
3./ called recurse_tree:
data: array(2 => array(4,5),4=>array(5,6));
level: 2
final: array();
tmp: array();
4./ called recurse_tree:
data: array(4,5)
level: 3
final: array();
tmp: array();
5./ called recurse_tree:
data: 4
level: 4
final: array(4 => 4)
tmp: array()
6./ called recurse_tree:
data: 5
level: 4
final: array(4 => 5)
tmp: array(4 => 4)
7./ called recurse_tree:
data: 5
level: 4
final: array(4=> 5)
tmp: array(4 => array(4,5))
8./ called recurse_tree:
data: 6
level: 4
final: array(4 => 6)
tmp: array(4 => array(4,5,5))
What is the best way to implement a Binary Tree recursion algorithm?
实现二叉树递归算法的最佳方法是什么？
回答by netcoder
If I understand correctly, this is what you want:
如果我理解正确，这就是你想要的：
function tree(array $data, &$tree = array(), $level = 0) {
// init
if (!isset($tree[$level])) $tree[$level] = array();
foreach ($data as $key => $value) {
// if value is an array, push the key and recurse through the array
if (is_array($value)) {
$tree[$level][] = $key;
tree($value, $tree, $level+1);
}
// otherwise, push the value
else {
$tree[$level][] = $value;
}
}
}
Use it like this:
像这样使用它：
$binary_tree = array(1 => array(2 => array(4,5),4=>array(5,6)));
tree($binary_tree, $output);
var_dump($output);
This gives you:
这给你：
array(3) {
[0]=>
array(1) {
[0]=>
int(1)
}
[1]=>
array(2) {
[0]=>
int(2)
[1]=>
int(4)
}
[2]=>
array(4) {
[0]=>
int(4)
[1]=>
int(5)
[2]=>
int(5)
[3]=>
int(6)
}
}
回答by vinay bhardwaj
This function in class Tree view
类树视图中的此函数
you have got a return of array which has all node value then you can arrange on below tree view .
你得到了一个包含所有节点值的数组的返回，然后你可以在树视图下面进行排列。
function getTreeDataFromReg($setid)
{
if(!empty($setid))
{
for($in=0 ;$in<7;$in++ )
{
if($setid[$in]>0)
{
$result=$this->selectQuery(
"tbl_registration"," * "," fl_reg_id ='".$setid[$in]."'",
" fl_placment_side ASC ");
$setar=mysql_fetch_array($result);
$leftid=$setar['fl_left_id'];
$rightid=$setar['fl_right_id'];
}else
{
$leftid=0;
$rightid=0;
}
switch($in)
{
case 0: $setid[1]=$leftid;
$setid[2]=$rightid;
break;
case 1: $setid[3]=$leftid;
$setid[4]=$rightid;
break;
case 2: $setid[5]=$leftid;
$setid[6]=$rightid;
break;
case 3: $setid[7]=$leftid;
$setid[8]=$rightid;
break;
case 4: $setid[9]=$leftid;
$setid[10]=$rightid;
break;
case 5: $setid[11]=$leftid;
$setid[12]=$rightid;
break;
case 6: $setid[13]=$leftid;
$setid[14]=$rightid;
break;
}
}
}
return $setid;
}
function printTreeView($parentid)
{
$setid=array($parentid);
$setarra=$this->getTreeDataFromReg($setid);
return $setarra;
}
Which creates a binary tree:
这创建了一个二叉树：
0
/ \
1 2
/ \ / \
3 4 5 6
/\ / \ /\ /\
