class Solution {

  public List<Interval> merge(Interval[] left, Interval[] right) {
    List<Interval> result = new ArrayList<Interval>();

    int l = 0;
    int r = 0;
    while (l < left.length && r < right.length) {
      // Skipping an interval from the left if it ends before an 
      // interval from the right starts
      if (left[l].end < right[r].start) {
        l++;
      // Similarly, skipping an interval from the right if it ends before 
      // an interval from the left starts
      } else if (right[r].end < left[l].start) {
        r++;
      } else {
        // If the first two conditions are not satisfied, there is an intersection.
        Interval intersection = new Interval(
          Math.max(left[l].start, right[r].start), 
          Math.min(left[l].end, right[r].end)
        );
        result.add(intersection);

        // Skipping the interval that ends first because the longer interval can 
        // still intersect with another interval
        if (left[l].end > right[r].end) {
          r++;
        } else {
          l++;
        }
      }
    }

    return result;
  }

}