Method checkDescendants

javascript/1993-operations-on-tree.js:107–119

* Helper method to check descendants * Time O(n) | Space O(n) * @param {number} index * @return {boolean}

(index)

     * @return {boolean}
     */
    checkDescendants(index) {
        const stack = [];
        stack.push(index);
        while (stack.length) {
            const node = stack.pop();
            const children = this.childHash[node];
            for (let i = 0; i < (children && children.length); i++) {
                if (this.treeHash[children[i]]) return true;
                stack.push(children[i]);
            }
        }
        return false;
    }
}