Minimum Number of Arrows to Burst Balloons

class Solution:
    def findMinArrowShots(self, points: List[List[int]]) -> int:
        points.sort()
        res = 0
        pos = float("-inf")
        for a, b in points:
            if a > pos:
                res += 1
                pos = b
            else:
                pos = min(pos, b)
        return res