C++ ,nms,非极大值计算

static int nms(int validCount, std::vector &outputLocations, std::vector classIds, std::vector &order, int filterId, float threshold)
{
    for (int i = 0; i < validCount; ++i)
    {
        if (order[i] == -1 || classIds[i] != filterId)
        {
            continue;
        }
        int n = order[i];
        for (int j = i + 1; j < validCount; ++j)
        {
            int m = order[j];
            if (m == -1 || classIds[i] != filterId)
            {
                continue;
            }
            float xmin0 = outputLocations[n * 4 + 0];
            float ymin0 = outputLocations[n * 4 + 1];
            float xmax0 = outputLocations[n * 4 + 0] + outputLocations[n * 4 + 2];
            float ymax0 = outputLocations[n * 4 + 1] + outputLocations[n * 4 + 3];

            float xmin1 = outputLocations[m * 4 + 0];
            float ymin1 = outputLocations[m * 4 + 1];
            float xmax1 = outputLocations[m * 4 + 0] + outputLocations[m * 4 + 2];
            float ymax1 = outputLocations[m * 4 + 1] + outputLocations[m * 4 + 3];

            float iou = CalculateOverlap(xmin0, ymin0, xmax0, ymax0, xmin1, ymin1, xmax1, ymax1);

            if (iou > threshold)
            {
                order[j] = -1;
            }
        }
    }
    return 0;
}

static float CalculateOverlap(float xmin0, float ymin0, float xmax0, float ymax0, float xmin1, float ymin1, float xmax1, float ymax1)
{
    float w = fmax(0.f, fmin(xmax0, xmax1) - fmax(xmin0, xmin1) + 1.0);
    float h = fmax(0.f, fmin(ymax0, ymax1) - fmax(ymin0, ymin1) + 1.0);
    float i = w * h;
    float u = (xmax0 - xmin0 + 1.0) * (ymax0 - ymin0 + 1.0) + (xmax1 - xmin1 + 1.0) * (ymax1 - ymin1 + 1.0) - i;
    return u <= 0.f ? 0.f : (i / u);
}