find_set_cover_all_intervals.dart

/// Task
/// Given a set of closed intervals, find the smallest set of numbers that covers all the intervals. If there are multiple smallest sets, return any of them.

Set findMinSetToCoverIntervals(List<List<int>> input) {
  var start;
  var end;

  /// we need to find minimum value of the end intervals, it will be our start in result
  /// and maximum value of the start intervals, it will be our end in result
  for (List<int> interval in input) {
    start ??= interval[1];
    end ??= interval[0];
    if (interval[0] > end) {
      end = interval[0];
    }
    if (interval[1] < start) {
      start = interval[1];
    }
  }

  return {start, end};
}

void main() {
  var result = findMinSetToCoverIntervals([
    [10, 20],
    [6, 9],
    [0, 3],
    [2, 6],
    [3, 4],
  ]);
  print(result);
  result = findMinSetToCoverIntervals([
    [0, 4],
    [2, 6],
    [0, 9]
  ]);
  print(result);
  result = findMinSetToCoverIntervals([
    [-20, 10],
    [50, 100],
    [-100, 0],
    [500, 501],
  ]);
  print(result);

  result = findMinSetToCoverIntervals([
    [0, 3],
    [2, 6],
    [3, 4],
    [6, 9],
  ]);
  print(result);
  result = findMinSetToCoverIntervals([
    [0, 10],
    [15, 20]
  ]);
  print(result);
}