Package g0501_0600.s0552_student_attendance_record_ii

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    552 - Student Attendance Record II\.

    Hard

    An attendance record for a student can be represented as a string where each character signifies whether the student was absent, late, or present on that day. The record only contains the following three characters:

    • 'A': Absent.

    • 'L': Late.

    • 'P': Present.

    Any student is eligible for an attendance award if they meet both of the following criteria:

    • The student was absent ('A') for strictly fewer than 2 days total.

    • The student was never late ('L') for 3 or more consecutive days.

    Given an integer n, return the number of possible attendance records of length n that make a student eligible for an attendance award. The answer may be very large, so return it modulo <code>10<sup>9</sup> + 7</code>.

    Example 1:

    Input: n = 2

    Output: 8

    Explanation: There are 8 records with length 2 that are eligible for an award: "PP", "AP", "PA", "LP", "PL", "AL", "LA", "LL" Only "AA" is not eligible because there are 2 absences (there need to be fewer than 2).

    Example 2:

    Input: n = 1

    Output: 3

    Example 3:

    Input: n = 10101

    Output: 183236316

    Constraints:

    • <code>1 <= n <= 10<sup>5</sup></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 checkRecord(Integer n)

      • Methods inherited from class java.lang.Object

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