ferry solve 1

    public static String solve(ArrayList<String> carList, double ferryLength, int numCars) {

        double capacity = ferryLength;
        int tripNum = 0;
        String output = tripNum + " " + ":";
        StringBuilder sb = new StringBuilder();
        sb.append(output);

        if (numCars == 0) {
            return "Day Off!";
        } else {
            ArrayList<String> leftBank = new ArrayList<String>();
            ArrayList<String> rightBank = new ArrayList<String>();
            ArrayDeque<String> boat = new ArrayDeque<String>();

            // add cars to respective banks
            for (String s : carList) {
                if (s.contains("left")) {
                    leftBank.add(s);
                } else {
                    rightBank.add(s);
                }
            }

            while (leftBank.size() != 0 && rightBank.size() != 0) {
                // check if left bank car can fit on boat
                for (int i = 0; i < leftBank.size(); i++) {
                    if (capacity >= 0) {
                        if (convert(getLength(leftBank.get(i))) <= capacity) {
                            boat.add(leftBank.get(i));
                            capacity = capacity - convert(getLength(leftBank.get(i)));
                            leftBank.remove(i);
                            i--;
                        } else {
                            tripNum++;
                            for (String car : boat) {
                                sb.append(" " + getPlate(car));
                                boat.pop();
                            }
                            sb.append("\n");
                            capacity = ferryLength;
                        }
                    }
                }

                // check if right bank car can fit on boat
                for (int i = 0; i < rightBank.size(); i++) {
                    if (capacity >= 0) {
                        if (convert(getLength(rightBank.get(i))) <= capacity) {
                            boat.add(rightBank.get(i));
                            capacity = capacity - convert(getLength(rightBank.get(i)));
                            rightBank.remove(i);
                            i--;
                        }
                        // capacity is full empty boat and add to output string
                    } else {
                        tripNum++;
                        sb.append(output);
                        for (String car : boat) {
                            sb.append(" " + getPlate(car));
                            boat.pop();
                        }
                        sb.append("\n");
                        capacity = ferryLength;
                    }
                }
            }
        }
        return sb.toString();
    }