题解 | #密码验证合格程序#

public class Program {
    public static void Main() {
        string line;
        while ((line = System.Console.ReadLine ()) != null) { // 注意 while 处理多个 case
            // 1 Basic check.
            bool valid = false;
            if (line.Length > 8) {
                int nLa=0, nUa=0, nNum=0, nOther=0;
                for (var i=0; i<line.Length; ++i) {
                    var c = line[i];
                    if ('a' <= c && c <= 'z') nLa = 1;
                    else if ('A' <= c  && c <= 'Z') nUa = 1;
                    else if ('0' <= c && c <= '9') nNum = 1;
                    else if (' ' == c || '\n' == c) {
                        // pass
                    } else nOther += 1;
                    if ((nLa+nUa+nNum+nOther) >= 3) {
                        valid = true;
                        break;
                    }
                }
            }
            if (valid) {
                for (var i=0; i<line.Length; ++i) {
                    var n = 0;
                    for (int j=i, k=0; j<line.Length && k<i; ++j, ++k) {
                        if (line[j] == line[k]) {
                            if (++n > 2) {
                                valid = false;
                                break;
                            }
                        } else {
                            j=i;  // Go back.
                            n = 0;
                        }
                    }
                    if (!valid) break;
                }
            }
            if (valid) System.Console.WriteLine("OK");
            else System.Console.WriteLine("NG");
        }
    }
}