This problem simply asks you to repeatedly calculate the distance between two consecutive points using the Pythagorean theorem or the distance formula $\sqrt{(y_2-y_1{)}^2+(x_2-x_1{)}^2}$. If the distance is less than or equal to $D$, increment a counter for the current combo; otherwise, update a counter for maximum combo if the current combo is greater, and then reset the current combo to 0. Make sure to update the coordinates of $x_1$ and $y_1$ to $x_2$ and $y_2$ so you're not just calculating distances from point 1 to all other points.

Time complexity: $\mathcal{O}(N)$