function setup() {
  createCanvas(400, 400);
  background(220);

  let balls = []; // 20 objects
  for (let i = 0; i < 20; i++) {
    // with random position and size (from 10-50)
    // [Your Code Here]
    random_size = random(10, 50);
    balls.push([
      random(0 + random_size / 2, 400 - random_size / 2),
      random(0 + random_size / 2, 400 - random_size / 2),
      random_size,
    ]);
  }

  drawBalls(balls);
  drawBoundingBox(balls);
}

function drawBalls(balls) {
  // [Your Code Here]
  num_balls = balls.length;

  for (let i = 0; i < num_balls; i++) {
    circle(balls[i][0], balls[i][1], balls[i][2]);
  }
}

// draws smallest rect fitting all balls
function drawBoundingBox(balls) {
  // [Your Code Here]
  box_top = 99999;
  box_left = 9999999;
  box_bottom = -1;
  box_right = -1;

  num_balls = balls.length;
  for (let i = 0; i < num_balls; i++) {
    circle_left = balls[i][0] - balls[i][2] / 2;
    circle_right = balls[i][0] + balls[i][2] / 2;
    circle_top = balls[i][1] - balls[i][2] / 2;
    circle_bottom = balls[i][1] + balls[i][2] / 2;

    box_top = min(box_top, circle_top);
    box_left = min(box_left, circle_left);
    box_bottom = max(box_bottom, circle_bottom);
    box_right = max(box_right, circle_right);
  }

  noFill();
  stroke('red');
  rect(box_left, box_top, box_right - box_left, box_bottom - box_top);
}