Function isSubtree

javascript/0572-subtree-of-another-tree.js:7–16

(root, subRoot)

 * @return {boolean}
 */
var isSubtree = function (root, subRoot) {
    if (!root) return false;

    if (isSame(root, subRoot)) return true;

    const hasLeftTree = isSubtree(root.left, subRoot);
    const hasRightTree = isSubtree(root.right, subRoot);

    return hasLeftTree || hasRightTree;
};

const isSame = (root, subRoot) => {
    const hasReachedEnd = !(root && subRoot);