lowest-common-ancestor-of-a-binary-tree.js

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {TreeNode} p
 * @param {TreeNode} q
 * @return {TreeNode}
 */

var lowestCommonAncestor = function(root, p, q) {
    if (root === null || root === p || root === q) 
        return root;
    let left = lowestCommonAncestor(root.left, p, q);
    let right = lowestCommonAncestor(root.right, p, q);
    
    return left === null ? right : (right === null ? left : root);
    
};