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# 452. Minimum Number of Arrows to Burst Balloons

## Description

There are some 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. The start is always smaller than the end.

An arrow can be shot up exactly vertically from different points along the x-axis. A balloon with `x`

and _{start}`x`

bursts by an arrow shot at _{end}`x`

if `x`

. There is no limit to the number of arrows that can be shot. An arrow once shot keeps traveling up infinitely._{start} ≤ x ≤ x_{end}

Given an array `points`

where `points[i] = [x`

, return _{start}, x_{end}]*the minimum number of arrows that must be shot to burst all balloons*.

**Example 1:**

Input:points = [[10,16],[2,8],[1,6],[7,12]]Output:2Explanation: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).

**Example 2:**

Input:points = [[1,2],[3,4],[5,6],[7,8]]Output:4

**Example 3:**

Input:points = [[1,2],[2,3],[3,4],[4,5]]Output:2

**Example 4:**

Input:points = [[1,2]]Output:1

**Example 5:**

Input:points = [[2,3],[2,3]]Output:1

**Constraints:**

`0 <= points.length <= 10`

^{4}`points[i].length == 2`

`-2`

^{31}<= x_{start}< x_{end}<= 2^{31}- 1