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mergeTwoBinaryTrees.php
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51 lines (40 loc) · 1.2 KB
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<?php
/**
* Definition for a binary tree node.
*
*/
class TreeNode
{
public $val = null;
public $left = null;
public $right = null;
function __construct($val = 0, $left = null, $right = null)
{
$this->val = $val;
$this->left = $left;
$this->right = $right;
}
}
/**
* 给定两个二叉树，想象当你将它们中的一个覆盖到另一个上时，两个二叉树的一些节点便会重叠。
* 你需要将他们合并为一个新的二叉树。合并的规则是如果两个节点重叠，那么将他们的值相加作为节点合并后的新值，否则不为 NULL 的节点将直接作为新二叉树的节点。
* 来源：力扣（LeetCode）
* 链接：https://leetcode-cn.com/problems/merge-two-binary-trees
* @param TreeNode $root1
* @param TreeNode $root2
* @return TreeNode
*/
function mergeTrees($root1, $root2)
{
if ($root1 === null) {
return $root2;
}
if ($root2 === null) {
return $root1;
}
$node = new TreeNode();
$node->val = $root1->val + $root2->val;
$node->left = mergeTrees($root1->left, $root2->left);
$node->right = mergeTrees($root1->right, $root2->right);
return $node;
}