sumArray

var sumArray = function(array) {
  let sums = [];
  const greatestSum = index => {
    let sum = 0;
    for (let i = index; i < array.length; i++) {
      sum += array[i];
      if (!sums[index] || sums[index] < sum) {
        sums[index] = sum;
      }
    }
    if (index === array.length - 1) {
      return;
    }
    greatestSum(index + 1);
  };
  greatestSum(0);
  return Math.max.apply(null, sums);
};