public class FixedHistogram implements Histogram {
    private double _low, _high; /* From constructor*/
    private int[] _count; /* Value counts */

    /** A new histogram with SIZE buckets of values >= LOW and < HIGH. */
    public FixedHistogram(int size, double low, double high)
    {
        if (low >= high || size <= 0) {
            throw new IllegalArgumentException();
        }
        _low = low; _high = high;
        _count = new int[size];
    }

    public int size() {
        return _count.length;
    }
    
    public double low(int k) {
        return _low + k * (_high - _low)/_count.length;
    }

    public int count(int k) {
        return _count[k];
    }

    public void add(double val) {
        if (val >= _low && val < _high) {
            _count[(int) ((val - _low)/(_high - _low) * _count.length)] += 1;
        }
    }
}