Watch 10 video solutions for Student Attendance Record II, a hard level problem involving Dynamic Programming. This walkthrough by NeetCodeIO has 10,077 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
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:
'A') for strictly fewer than 2 days total.'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.
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:
1 <= n <= 105