minimum-number-of-arrows-to-burst-balloons.js

/**
 * Minimum Number of Arrows to Burst Balloons
 *
 * There are a number of spherical balloons spread in two-dimensional space. For each balloon, provided
 * input is the start and end coordinates of the horizontal diameter. Since it's horizontal, y-coordinates
 * don't matter and hence the x-coordinates of start and end of the diameter suffice. Start is always
 * smaller than end. There will be at most 104 balloons.
 *
 * An arrow can be shot up exactly vertically from different points along the x-axis. A balloon with xstart
 * and xend bursts by an arrow shot at x if xstart ≤ x ≤ xend. There is no limit to the number of arrows that
 * can be shot. An arrow once shot keeps travelling up infinitely. The problem is to find the minimum number
 * of arrows that must be shot to burst all balloons.
 *
 * Example:
 *
 * Input:
 * [[10,16], [2,8], [1,6], [7,12]]
 *
 * Output:
 * 2
 *
 * Explanation:
 * One way is to shoot one arrow for example at x = 6 (bursting the balloons [2,8] and [1,6]) and another
 * arrow at x = 11 (bursting the other two balloons).
 */

/**
 * @param {number[][]} points
 * @return {number}
 */
const findMinArrowShots = points => {
  if (points.length === 0) {
    return 0;
  }

  points.sort((a, b) => a[1] - b[1]);

  let end = points[0][1];
  let count = 1;

  for (let i = 1; i < points.length; i++) {
    if (end >= points[i][0]) {
      continue;
    }
    count++;
    end = points[i][1];
  }

  return count;
};

export { findMinArrowShots };