// ArrayList utils: could be moved to AList.
Object randomOneOf(ArrayList a) {
  return a.get(randomInt(a.size()));
}
Object lastOf(ArrayList a) {
  return a.get(a.size()-1);
}
Object firstOf(ArrayList a) {
  return a.get(0);
}
Object minOf(ArrayList a) {
  return Collections.min(a);
}
int minIndexOf(ArrayList a) {
  return a.indexOf(minOf(a));
}
Object maxOf(ArrayList a) {
  return Collections.max(a);
}
int maxIndexOf(ArrayList a) {
  return a.indexOf(maxOf(a));
}
ArrayList randomNOf(ArrayList a, int n) { // could return List, but...
  ArrayList b = (ArrayList)a.clone();
  java.util.Collections.shuffle(b);
  return new ArrayList(b.subList(0,n));
}
void removeAll(ArrayList a, Object o) {
  while(a.remove(o)) ;
}

// Random int/color utils
int randomInt(int f) { // return random int i in [0,n)
  return floor(random (f));
}
int randomInt(int f1, int f2) { // return random int i in [0,n)
  return floor(random (f1, f2));
}
color randomBrightColor() {
  int r = 255*round(random(1));
  int g = 255*round(random(1));
  int b = 255*round(random(1));
  if (r == g && g == b && b == 0) {
    return randomBrightColor();
  }
  return color(r,g,b);
}

// Turn arrays into strings, mainly for printing.
String toString(int[] a) {
  String s = "[";
  for(int i = 0; i<a.length; i++)
    s += (i==0?"":" ") + a[i];
  return s+"]";
}
String toString(float[] a) {
  String s = "[";
  for(int i = 0; i<a.length; i++)
    s += (i==0?"":" ") + a[i];
  return s+"]";
}
String objectsToString(Object[] a) {
  String s = "[";
  for(int i = 0; i<a.length; i++)
    s += (i==0?"":" ") + a[i];
  return s+"]";
}
String arrayListToString(ArrayList a) {
  return objectsToString(a.toArray());
}
String mapToString(HashMap m) {
  return "["+m+"]";
}

// Formatting, Date & Time
String MDY (String seperator) {
  DecimalFormat fmt = new DecimalFormat("00");
  return fmt.format(month())+seperator+fmt.format(day())+seperator+((""+year()).substring(2));
}
String HM (String seperator) {
  DecimalFormat fmt = new DecimalFormat("00");
  return fmt.format(hour())+seperator+fmt.format(second());
}
DecimalFormat float1place = new DecimalFormat("#.0"); //Performance: make this just once.
String NF (float f) {
  return float1place.format(f);
}


// I/O
PrintWriter openPrintWriter(String fileName) {
  PrintWriter out = null;
  try {
    out = new PrintWriter(new BufferedWriter(new FileWriter(fileName)));
  }
  catch (Exception e) {
    println ("Oops: error opening output file "+fileName+" exception: "+e);
  }
  return out;
}

BufferedWriter openBufferedWriter(String fileName) {
  BufferedWriter out = null;
  try {
    out = new BufferedWriter(new FileWriter(fileName)); // ,"UTF-8"
  }
  catch (Exception e) {
    println ("Oops: error opening output file "+fileName+" exception: "+e);
  }
  return out;
}

void closeWriter(Writer writer) {
  try {
    writer.close();
  }
  catch (Exception e) {
    println ("Oops: error closing output file; exception: "+e);
  }
}
void writeWriter(Writer writer, String s) {
  try {
    writer.write(s);
  }
  catch (Exception e) {
    println ("Oops: error writing to output file; exception: "+e);
  }
}