import java.util.*;

public class ArrayIntList implements IntList {
    private int[] elementData; // list of integers
    private int size;          // current number of elements in the list

    public static final int DEFAULT_CAPACITY = 100;

    public ArrayIntList() {
        this(DEFAULT_CAPACITY);
    }

    public ArrayIntList(int capacity) {
        if (capacity < 0) {
            throw new IllegalArgumentException("capacity: " + capacity);
        }
        elementData = new int[capacity];
        size = 0;
    }

    public int size() {
        return size;
    }

    public int get(int index) {
        checkIndex(index);
        return elementData[index];
    }

    public String toString() {
        if (size == 0) {
            return "[]";
        } else {
            String result = "[" + elementData[0];
            for (int i = 1; i < size; i++) {
                result += ", " + elementData[i];
            }
            result += "]";
            return result;
        }
    }

    public int indexOf(int value) {
        for (int i = 0; i < size; i++) {
            if (elementData[i] == value) {
                return i;
            }
        }
        return -1;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public boolean contains(int value) {
        return indexOf(value) >= 0;
    }

    public void add(int value) {
        add(size, value);
    }

    public void add(int index, int value) {
        if (index < 0 || index > size) {
            throw new IndexOutOfBoundsException("index: " + index);
        }
        ensureCapacity(size + 1);
        for (int i = size; i > index; i--) {
            elementData[i] = elementData[i - 1];
        }
        elementData[index] = value;
        size++;
    }

    public void set(int index, int value) {
        checkIndex(index);
        elementData[index] = value;
    }

    public void clear() {
        size = 0;
    }

    public void remove(int index) {
        checkIndex(index);
        for (int i = index; i < size - 1; i++) {
            elementData[i] = elementData[i + 1];
        }
        size--;
    }
    
    public Iterator<Integer> iterator() {
        return new ArrayIntListIterator();
    }

    private void checkIndex(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException("index: " + index);
        }
    }

    public void ensureCapacity(int capacity) {
        if (capacity > elementData.length) {
            int newCapacity = elementData.length * 2 + 1;
            if (capacity > newCapacity) {
                newCapacity = capacity;
            }
            elementData = Arrays.copyOf(elementData, newCapacity);
        }
    }
    
    private class ArrayIntListIterator implements Iterator<Integer> {
        private int position;           // current position within the list
        private boolean removeOK;       // whether it's okay to remove now

        // pre : list != null
        // post: constructs an iterator for the given list
        public ArrayIntListIterator() {
            position = 0;
            removeOK = false;
        }

        // post: returns true if there are more elements left, false otherwise
        public boolean hasNext() {
            return position < size();
        }

        // pre : hasNext()
        // post: returns the next element in the iteration
        public Integer next() {
            if (!hasNext()) {
                throw new NoSuchElementException();
            }
            int result = get(position);
            position++;
            removeOK = true;
            return result;
        }

        // pre : next() has been called without a call on remove (i.e., at most one
        //       call per call on next)
        // post: removes the last element returned by the iterator
        public void remove() {
            if (!removeOK) {
                throw new IllegalStateException();
            }
            ArrayIntList.this.remove(position - 1);
            position--;
            removeOK = false;
        }
    }
}