Function isValidBST

javascript/0098-validate-binary-search-tree.js:7–15

(root, min = -Infinity, max = Infinity)

 * @return {boolean}
 */
var isValidBST = function (root, min = -Infinity, max = Infinity) {
    const isBaseCase = root === null;
    if (isBaseCase) return true;

    const isInvalid = root.val <= min || max <= root.val;
    if (isInvalid) return false;

    return dfs(root, min, max);
};

const dfs = (root, min, max) => {
    const left = isValidBST(root.left, min, root.val);