diameter of binary tree javascript
/**
* Calculate diameter with center `root`
* @param {TreeNode} root
* @returns {number}
*/
const countDiameter = root => {
if (!root) return 0;
return 1 + Math.max(countDiameter(root.left), countDiameter(root.right));
};
/**
* @param {TreeNode} root
* @returns {number}
*/
const diameterOfBinaryTree = root => {
if (!root) return 0;
const center = countDiameter(root.left) + countDiameter(root.right);
const left = diameterOfBinaryTree(root.left);
const right = diameterOfBinaryTree(root.right);
return Math.max(center, left, right);
};