It's an API server in go that deals with a series of points represented as (x,y) coordinates on a simple 2-dimensional plane. Take a look at https://en.wikipedia.org/wiki/Cartesian_coordinate_system if you need a refresher on this concept.
GET /api/points?x={d}&y={y}&distance={distance}
xinteger (required). This represents thexcoordinate of the search origin.yinteger (required). This represents theycoordinate of the search origin.distanceinteger (required). This represents the Manhattan distance; points withindistancefromxandyare returned, points outside are filtered out.
Returns a JSON list of points that are within distance from x,y, using the Manhattan distance method. The points are returned in order of increasing distance from the search origin.
The Manhattan distance is measured "block-wise", as the distance in blocks between any two points in the plane (e.g. 2 blocks down and 3 blocks over for a total of 5 blocks). It is defined as the sum of the horizontal and vertical distances between points on a grid. Formally, where p1 = (x1, y1) and p2 = (x2, y2), distance(p1,p2) = |x1-x2| + |y1-y2|.
On startup, the API server read a list of points from data/points.json.
go build && ./cartesian-go-api
curl -s http://127.0.0.1:8000/api/points\?x\=10\&y\=20\&distance\=20
go test