// LLP-NearestNeighbor: find nearest neighbor distance for each point.
// px[j], py[j] are x,y coordinates of point j.

class LLPNearestNeighbor {
  void LLPNearestNeighbor(double[] px, double[] py) {
    double[] G = infinity;
    forbidden (j) : G[j] > nearestDist(px, py, j) =>
      advance : G[j] = nearestDist(px, py, j);
  }

  double nearestDist(double[] px, double[] py, int j) {
    double best = infinity;
    int k = 0;
    while (k < px.length) {
      if (k != j) {
        double d = dist(px, py, j, k);
        if (d < best) { best = d; }
      };
      k = k + 1;
    };
    return best;
  }

  double dist(double[] px, double[] py, int j, int k) {
    double dx = px[j] - px[k];
    double dy = py[j] - py[k];
    return dx * dx + dy * dy;
  }
}