2331. Evaluate Boolean Binary Tree

Easy

You are given the root of a full binary tree with the following properties:

• Leaf nodes have either the value 0 or 1, where 0 represents False and 1 represents True.
• Non-leaf nodes have either the value 2 or 3, where 2 represents the boolean OR and 3 represents the boolean AND.

The evaluation of a node is as follows:

• If the node is a leaf node, the evaluation is the value of the node, i.e. True or False.
• Otherwise, evaluate the node's two children and apply the boolean operation of its value with the children's evaluations.

Return the boolean result of evaluating the root node.

A full binary tree is a binary tree where each node has either 0 or 2 children.

A leaf node is a node that has zero children.

Example 1:

• Input: root = [2,1,3,null,null,0,1]
• Output: true
• Explanation: The above diagram illustrates the evaluation process.

The AND node evaluates to False AND True = False.

The OR node evaluates to True OR False = True.

The root node evaluates to True, so we return true.

Example 2:

• Input: root = [0]
• Output: false
• Explanation: The root node is a leaf node, and it evaluates to false, so we return false.

Constraints:

• The number of nodes in the tree is in the range [1, 1000].
• 0 <= Node.val <= 3
• Every node has either 0 or 2 children.
• Leaf nodes have a value of 0 or 1.
• Non-leaf nodes have a value of 2 or 3.

Solution:

/**
 * 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;
 *     }
 * }
 */
class Solution {

    /**
     * @param TreeNode $root
     * @return Boolean
     */
    function evaluateTree($root) {
        if ($root->val < 2){
            $return = $root->val;
        }elseif ($root->val == 2){
            $return = $this->evaluateTree($root->left) || $this->evaluateTree($root->right);
        }else{
            $return = $this->evaluateTree($root->left) && $this->evaluateTree($root->right);
        }
        return $return;
    }
}

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