[failsafe]

The interesting part is solving the "closest pair problem" which is a part of the clustering algorithm. Hurts my head just thinking about it, god knows how someone came up with a solution like this. https://www.geeksforgeeks.org/closest-pair-of-points-using-d...

[n4r9]

The closest-pair algorithm is something you might use in single-linkage clustering, not K-means clustering:

https://en.wikipedia.org/wiki/Single-linkage_clustering