Use a max-heap of size k to track the k closest points seen so far.
Why max-heap? Because you want quick access to the farthest point among your current candidates. When a new point is closer than your farthest candidate, you evict the farthest and add the new point.
Iterate through points:
- If heap size <
k, add the point. - If point is closer than heap max, replace the max with this point.
After processing all points, the heap contains the k closest.