gistfile1.txt

function formatSchedule(schedules) {

  var dayAbbr = [ 'Пн', 'Вт', 'Ср', 'Чт', 'Пт', 'Сб', 'Вс' ];
  function dayIndicesToWord(indices) {
    if (areDayIndicesSequential(indices)) {
      return dayAbbr[indices[0]] + '-' + dayAbbr[_.last(indices)];
    }
    else {
      var daysAsWords = _.map(indices, function(index) {
        return dayAbbr[index];
      });
      return daysAsWords.join(',');
    }
  }

  var hoursPairs = _.pluck(schedules, '0');
  var hours = _.map(hoursPairs, function(o) {
    return o.from + '-' + o.to;
  });

  var daysGroupedByHours = _.reduce(hours, function(memo, hour, dayIndex) {
    if (!memo[hour]) {
      memo[hour] = [ ]
    }
    memo[hour].push(dayIndex);
    return memo;
  }, { });

  var resultStr = _.reduce(daysGroupedByHours, function(str, dayIndices, hour) {
    str += dayIndicesToWord(dayIndices) + ': ' + hour + ' ';
    return str;
  }, '');

  return resultStr;
}