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var goodNodes = function(root) {
    let answer = 0;
    
    const dfs = (node, max) => {
        if(!node) return;
        
        if(node.val >= max) answer += 1;
	      max = Math.max(node.val, max);
        
        node.right && dfs(node.right, max);
        node.left && dfs(node.left, max);
    }
    
    dfs(root, root.val);
    
    return answer;
};


/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var goodNodes = function(root) {
    let cnt = 0;
    
    const dfs = (node, maxValue) => {
        if (!node) return;
        
        const currMaxValue = Math.max(maxValue, node.val); 
        if (node.val === currMaxValue) cnt += 1;
        
        if (node.left) dfs(node.left, currMaxValue)
        if (node.right) dfs(node.right, currMaxValue)
    }
    
    dfs(root, -10001);
    
    return cnt;
};

Count Good Nodes in Binary Tree

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