551. Student Attendance Record I

You are given a string representing an attendance record for a student. The record only contains the following three characters:

1. 'A' : Absent.
2. 'L' : Late.
3. 'P' : Present.

 A student could be rewarded if his attendance record doesn't contain more than one 'A' (absent) or more than two continuous 'L' (late).

You need to return whether the student could be rewarded according to his attendance record.

Example 1:

Input: "PPALLP"
Output: True

 Example 2:

Input: "PPALLL"
Output: False

 题目含义：

您将获得一个代表学生考勤记录的字符串。该记录仅包含以下三个字符：

‘A’：没有 
‘L’：晚了 
‘P’：现在。 
如果出席记录不包含多于一个“A”（缺席）或超过两个连续的“L”（晚），学生可以获得奖励。

你需要返回是否可以根据出勤记录来奖励学生。

示例1： 
输入： “PPALLP” 
输出： True 
示例2： 
输入： “PPALLL” 
输出： False

    public boolean checkRecord(String s) {
        int countA = 0;
        char[] letter = s.toCharArray();
        int letterLeghth = letter.length;
        for (int i=0;i<letterLeghth-2;i++)
        {
            if (letter[i] == 'A') countA++;
            else if (letter[i] == 'L')
            {
                if (letter[i+1] == 'L' && letter[i+2]=='L')
                    return false;
            }
        }
        if (letterLeghth>=2)
        {
            if (letter[letterLeghth-1] == 'A') countA++;
            if (letter[letter.length-2] == 'A') countA++;  
        }
        return countA>1?false:true;
    }