blah..dart

import 'dart:math';
import 'dart:io';

var random = Random();

List<int> makeRandom(int n) {
  var x = List<int>(n);
  for (int i = 0; i < n; i++) {
    x[i] = random.nextInt(n * 10);
  }
  return x;
}

List<int> makeDiff(List<int> nums) {
  var n = nums.length;
  var xx = List<int>(n * n);
  for (int j = 1; j < n; j++) {
    for (int i = 0; i < n && i + j < n; i++) {
      xx[j * n + i + j - 1] = nums[i + j] - nums[i];
    }
  }
  return xx;
}

void main() {
  var n = 30;
  var nums = makeRandom(n);
  nums.sort();

  for (int k = 0; k < 2; k++) {
    var n1 = random.nextInt(n);
    var n2 = random.nextInt(n);

    var v1 = nums[n1];
    var v2 = nums[n2];
    nums[n1] = v2;
    nums[n2] = v1;
  }

  //nums.shuffle();
  var nums2 = makeDiff(nums);
  for (int i = 0; i < n; i++) {
    var num = nums[i];
    var snum = num.toString().padLeft(5);
    stdout.write(snum);
  }
  print("");
  for (int j = 1; j < n; j++) {
    for (int i = 0; i < n; i++) {
      var num = nums2[j * n + i];
      var snum = (num != null) ? (num >= 0 ? num.toString() : '___') : '****';
      snum = snum.padLeft(5);
      stdout.write(snum);
    }
    stdout.write('\n');
  }
}