Minimum Number of Arrows to Burst Balloons.swift

// https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/description/?envType=study-plan-v2&envId=leetcode-75

/*
There are some spherical balloons taped onto a flat wall that represents the XY-plane. The balloons are represented as a 2D integer array points where points[i] = [xstart, xend] denotes a balloon whose horizontal diameter stretches between xstart and xend. You do not know the exact y-coordinates of the balloons.

Arrows can be shot up directly vertically (in the positive y-direction) from different points along the x-axis. A balloon with xstart and xend is burst by an arrow shot at x if xstart <= x <= xend. There is no limit to the number of arrows that can be shot. A shot arrow keeps traveling up infinitely, bursting any balloons in its path.

Given the array points, return the minimum number of arrows that must be shot to burst all balloons.
*/

class Solution {
    func findMinArrowShots(_ points: [[Int]]) -> Int {
        var points = points.sorted{
            $0[1] <  $1[1]
        }
        var arrows = 1

        var end = points[0][1]

        for i in 1..<points.count {
            if points[i][0] > end {
                arrows += 1
                end = points[i][1]
            }
        } 

        return arrows
    }
}