presto-main/src/main/java/io/prestosql/operator/aggregation/NumericHistogram.java/NumericHistogram/mergeSameBuckets
class NumericHistogram:    private static int mergeSameBuckets(double[] values, double[] weights, int nextIndex)
    {
        sort(values, weights, nextIndex);

        int current = 0;
        for (int i = 1; i < nextIndex; i++) {
            if (values[current] == values[i]) {
                weights[current] += weights[i];
            }
            else {
                current++;
                values[current] = values[i];
                weights[current] = weights[i];
            }
        }
        return current + 1;
    }