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:
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
109 + 7.
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).
Input: n = 1 Output: 3
Input: n = 10101 Output: 183236316
1 <= n <= 105