Finding all combinations of well-formed brackets

Question

This came up while talking to a friend and I thought I\'d ask here since it\'s an interesting problem and would like to see other people\'s solutions.

The task is to

Answer 1

  validParentheses: function validParentheses(n) {
    if(n === 1) {
      return ['()'];
    }
    var prevParentheses = validParentheses(n-1);
    var list = {};
    prevParentheses.forEach(function(item) {
      list['(' + item + ')'] = null;
      list['()' + item] = null;
      list[item + '()'] = null;
    });
    return Object.keys(list);
  }