|
| 1 | +<h2><a href="https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons">452. Minimum Number of Arrows to Burst Balloons</a></h2><h3>Medium</h3><hr><p>There are some spherical balloons taped onto a flat wall that represents the XY-plane. The balloons are represented as a 2D integer array <code>points</code> where <code>points[i] = [x<sub>start</sub>, x<sub>end</sub>]</code> denotes a balloon whose <strong>horizontal diameter</strong> stretches between <code>x<sub>start</sub></code> and <code>x<sub>end</sub></code>. You do not know the exact y-coordinates of the balloons.</p> |
| 2 | + |
| 3 | +<p>Arrows can be shot up <strong>directly vertically</strong> (in the positive y-direction) from different points along the x-axis. A balloon with <code>x<sub>start</sub></code> and <code>x<sub>end</sub></code> is <strong>burst</strong> by an arrow shot at <code>x</code> if <code>x<sub>start</sub> <= x <= x<sub>end</sub></code>. There is <strong>no limit</strong> to the number of arrows that can be shot. A shot arrow keeps traveling up infinitely, bursting any balloons in its path.</p> |
| 4 | + |
| 5 | +<p>Given the array <code>points</code>, return <em>the <strong>minimum</strong> number of arrows that must be shot to burst all balloons</em>.</p> |
| 6 | + |
| 7 | +<p> </p> |
| 8 | +<p><strong class="example">Example 1:</strong></p> |
| 9 | + |
| 10 | +<pre> |
| 11 | +<strong>Input:</strong> points = [[10,16],[2,8],[1,6],[7,12]] |
| 12 | +<strong>Output:</strong> 2 |
| 13 | +<strong>Explanation:</strong> The balloons can be burst by 2 arrows: |
| 14 | +- Shoot an arrow at x = 6, bursting the balloons [2,8] and [1,6]. |
| 15 | +- Shoot an arrow at x = 11, bursting the balloons [10,16] and [7,12]. |
| 16 | +</pre> |
| 17 | + |
| 18 | +<p><strong class="example">Example 2:</strong></p> |
| 19 | + |
| 20 | +<pre> |
| 21 | +<strong>Input:</strong> points = [[1,2],[3,4],[5,6],[7,8]] |
| 22 | +<strong>Output:</strong> 4 |
| 23 | +<strong>Explanation:</strong> One arrow needs to be shot for each balloon for a total of 4 arrows. |
| 24 | +</pre> |
| 25 | + |
| 26 | +<p><strong class="example">Example 3:</strong></p> |
| 27 | + |
| 28 | +<pre> |
| 29 | +<strong>Input:</strong> points = [[1,2],[2,3],[3,4],[4,5]] |
| 30 | +<strong>Output:</strong> 2 |
| 31 | +<strong>Explanation:</strong> The balloons can be burst by 2 arrows: |
| 32 | +- Shoot an arrow at x = 2, bursting the balloons [1,2] and [2,3]. |
| 33 | +- Shoot an arrow at x = 4, bursting the balloons [3,4] and [4,5]. |
| 34 | +</pre> |
| 35 | + |
| 36 | +<p> </p> |
| 37 | +<p><strong>Constraints:</strong></p> |
| 38 | + |
| 39 | +<ul> |
| 40 | + <li><code>1 <= points.length <= 10<sup>5</sup></code></li> |
| 41 | + <li><code>points[i].length == 2</code></li> |
| 42 | + <li><code>-2<sup>31</sup> <= x<sub>start</sub> < x<sub>end</sub> <= 2<sup>31</sup> - 1</code></li> |
| 43 | +</ul> |
0 commit comments