Package g0401_0500.s0452_minimum_number_of_arrows_to_burst_balloons

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    452 - Minimum Number of Arrows to Burst Balloons.

    Medium

    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 <code>pointsi = x<sub>start</sub>, x<sub>end</sub></code> denotes a balloon whose horizontal diameter 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.

    Arrows can be shot up directly vertically (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 burst by an arrow shot at x if <code>x<sub>start</sub><= x <= x<sub>end</sub></code>. 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.

    Example 1:

    Input: points = [10,16,2,8,1,6,7,12]

    Output: 2

    Explanation: The balloons can be burst by 2 arrows:

    • Shoot an arrow at x = 6, bursting the balloons 2,8 and 1,6.

    • Shoot an arrow at x = 11, bursting the balloons 10,16 and 7,12.

    Example 2:

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

    Output: 4

    Explanation: One arrow needs to be shot for each balloon for a total of 4 arrows.

    Example 3:

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

    Output: 2

    Explanation: The balloons can be burst by 2 arrows:

    • Shoot an arrow at x = 2, bursting the balloons 1,2 and 2,3.

    • Shoot an arrow at x = 4, bursting the balloons 3,4 and 4,5.

    Constraints:

    • <code>1 <= points.length <= 10<sup>5</sup></code>

    • points[i].length == 2

    • <code>-2<sup>31</sup><= x<sub>start</sub>< x<sub>end</sub><= 2<sup>31</sup> - 1</code>

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer findMinArrowShots(Array<IntArray> points)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait