static double ai_analysisMultiMap_percentageSolved(Map<O, MultiSet<S>> map) {
  int correct = 0, total = 0;
  for (O key, MultiSet<S> value : map) {
    total += l(value);
    if (value.uniqueSize() == 1) correct += l(value);
  }
  ret doubleRatio(correct*100, total);
}