Student Attendance Record I · Interview Problem

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Leetcode

Medium

Arrays

Strings

Simulation

Student Attendance Record I

Determine whether a student's attendance record is acceptable under simple absence and lateness rules.

Acceptance 0%

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Problem Statement

Problem

You are given a string representing a student's attendance record over several days.

Each character is one of:

A for an absence
L for being late
P for being present

An attendance record is considered acceptable if:

It contains at most one A.
It does not contain three or more consecutive L characters.

Return whether the record is valid.

Notes

You only need to check the whole string once. The task is to validate the sequence against the two rules above.

Input Format

A single string s consisting only of the characters A, L, and P.

Output Format

Return true if the record is acceptable, otherwise return false.

Constraints

1 <= s.length <= 1000 is a reasonable interview-style assumption for this problem.
s[i] ∈ { 'A', 'L', 'P' }.
The record is valid only if it has at most one A and no substring LLL.

Examples

Sample cases returned by the problem API.

Example 1

Input

s = "PPALLP"

Output

true

Explanation

There is one absence and no three consecutive lates.

Example 2

Input

s = "PPALLL"

Output

false

Explanation

The record contains three consecutive L characters at the end.

Show 1 more example

Example 3

Input

s = "PAAP"

Output

false

Explanation

The record contains two absences.

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