public abstract class PatternPrinter {
private int patternLength;
public PatternPrinter(int patternLength) {
this.patternLength = patternLength;
Random rnd = new Random();
int specialIndex = rnd.Next(patternLength);
for (int i=0;i<patternLength;i++) {
if (roll == 0) PrintNormal();
public abstract void PrintNormal();
public abstract void PrintVariant();
public abstract void PrintSpecial();
public class RiverPattern{
public RiverPattern(int patternlength){
public static void Main()
RiverPattern river = new RiverPattern(10);