The description is very unclear
- will the location be in increasing order?
- will there any gap between locations?
- if the input is , , the answer should be 1 instead of 0. If the radius is 0, it is just a point without range and making no sense.
- the explanation of example 2 is not right. It should say "We need to use radius 1 standard".
These are all not described clearly in the problem.