Package g0901_1000.s0920_number_of_music_playlists

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    920 - Number of Music Playlists.

    Hard

    Your music player contains n different songs. You want to listen to goal songs (not necessarily different) during your trip. To avoid boredom, you will create a playlist so that:

    • Every song is played at least once.

    • A song can only be played again only if k other songs have been played.

    Given n, goal, and k, return the number of possible playlists that you can create. Since the answer can be very large, return it modulo <code>10<sup>9</sup> + 7</code>.

    Example 1:

    Input: n = 3, goal = 3, k = 1

    Output: 6

    Explanation: There are 6 possible playlists: 1, 2, 3, 1, 3, 2, 2, 1, 3, 2, 3, 1, 3, 1, 2, and 3, 2, 1.

    Example 2:

    Input: n = 2, goal = 3, k = 0

    Output: 6

    Explanation: There are 6 possible playlists: 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 2, 1, 2, 1, 2, and 1, 2, 2.

    Example 3:

    Input: n = 2, goal = 3, k = 1

    Output: 2

    Explanation: There are 2 possible playlists: 1, 2, 1 and 2, 1, 2.

    Constraints:

    • 0 &lt;= k &lt; n &lt;= goal &lt;= 100

    • 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 numMusicPlaylists(Integer n, Integer l, Integer k)

      • Methods inherited from class java.lang.Object

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