dfs = (n, combos = [], open = 0, close = 0, path = []) => {
    const isBaseCase = (path.length === (n * 2));
    if (isBaseCase) {
        combos.push(path.join(''));/* Space O(N + N) */

        return combos; 
    }

    const isOpen = open < n;
    if (isOpen) backTrackOpen(n, combos, open, close, path);  /* Time O(2^N) | Space O(2^N) */

    const isClose = close < open;
    if (isClose) backTrackClose(n, combos, open, close, path);/* Time O(2^N) | Space O(2^N) */

    return combos;
}
DFS
Time O(((4^N) / (N * SQRT(N)))) | Space O(((4^N) / (N * SQRT(N))))
Time O(2^N) | Space O(2^N)
https://leetcode.com/problems/generate-parentheses
@param {number} n
@return {string[]}