A rare Pokémon has appeared on your radar, you think it might be a Lapras, and you’re trying to track it down. As you’re walking down a straight road, you notice that your radar changes its distance indicator from 3 footprints (within 1 km) to 2 footprints (within 100 m) at point A. Then, after walking another 100 m, the distance indicator goes back up to 3 footprints at point B.
I assume that "footprints" is a unit of length in PokemonGo which I haven't played.
Exactly, how the change is taking place in different distances in 2 situations?
It would be nice if you'll supplement your answer with a figure or something.
NB- It is a part of a problem of an ongoing contest and I'm not looking for any hints or solutions but I just seeks the understanding of the meaning of the sentence given above.
"Footprints" is not a unit of length since $3$ footprints $\ne \frac32 $ $2$ footprints. In other words, more footprints means further away, but the relationship isn't necessarily linear.
Imagine yourself at the center of a circle of radius $100$ m. Then any Pokemon within that circle is $2$ footprints (or closer) to you. If a Pokemon is outside of that circle, but still within a bigger $1$ km circle, then it will appear as $3$ footprints away.
Alternatively, you can think of it as concentric circles around the Pokemon like in the following diagram: