A geohash encodes a latitude and longitude as a short string. Each additional character identifies a smaller cell, so nearby points often share a prefix that can be used by a spatial index.
Design a GeohashEncoder class:
GeohashEncoder() creates a stateless encoder.string encode(double latitude, double longitude, int precision) returns exactly precision geohash characters.
Start with longitude range [-180, 180] and latitude range [-90, 90]. Generate bits by alternating dimensions, beginning with longitude. For the active range:
- If the coordinate is at least the midpoint, emit
1 and keep the upper half. - Otherwise, emit
0 and keep the lower half.
Group every five bits from most significant to least significant and map values 0 through 31 through:
Each call starts from the full coordinate ranges.
Example 1:
Input:
Output:
Explanation: Twenty-five alternating range decisions encode San Francisco as 9q8yy.
Example 2:
Input:
Output:
Explanation: At precision 6, London's coordinate cell is represented by gcpvj0.
Constraints
-90 <= latitude <= 90-180 <= longitude <= 1801 <= precision <= 12- Inputs are finite numbers.
- At most
100 calls are made to encode.
Encode a Geohashmedium