Datacenter Router Command Processor

Datacenter Router: Command Processor Implement process_commands(commands) to process a list of command strings in order and return one output string per command. Input: commands is an array of strings, one command per line. Output: an array of strings, one result per command in order. Maintain a set of datacenters with fields: name (unique) lat (latitude) lon (longitude) capacity (positive integer) healthy (initially true) load (initially 0) Use Earth radius R = 6371 km. Command 1: REGISTER Format: REGISTER name lat lon capacity Validation (return ERROR if any fails): lat in [-90, 90] inclusive lon in [-180, 180] inclusive capacity > 0 name must be unique (not previously registered) On success: create the datacenter with healthy=true, load=0, and return OK. Command 2: SET_HEALTHY Format: SET_HEALTHY name true/false Rules: If name does not exist: return ERROR Otherwise update the health flag and return OK Command 3: DISTANCE Format: DISTANCE lat1 lon1 lat2 lon2 Rules: Validate: lat1, lat2 ∈ [-90, 90] and lon1, lon2 ∈ [-180, 180]; if any out of range return ERROR Compute great-circle distance using the Haversine formula (R=6371) Return the distance rounded to the nearest integer (km) as a string Command 4: ROUTE (distance-based load balancing) Format: ROUTE lat lon Algorithm: Filter: keep only datacenters with healthy == true Sort: compute Haversine distance from (lat, lon) to each healthy datacenter; sort by ascending distance tie-break by name alphabetically Select: scan the sorted list and pick the first datacenter with load < capacity Update & Output: If found: increment its load by 1 and return: <chosen_name> <distance_rounded> <healthy_list> If none found (all healthy datacenters are full): return: None <healthy_list> Where: <distance_rounded> is the rounded distance to the chosen datacenter <healthy_list> is a comma-separated list of all healthy datacenter names in the sorted order from step 2 (include full ones too) Test Cases (5) Case 1 (REGISTER validation + SET_HEALTHY) input 7 REGISTER us-west 38 -122 100 REGISTER us-east 41 -74 150 REGISTER us-west 50 -100 50 REGISTER invalid-node 91 0 100 REGISTER invalid-cap 0 0 0 SET_HEALTHY us-east false SET_HEALTHY fake-node true output OK OK ERROR ERROR ERROR OK ERROR Case 2 (DISTANCE basics) input 3 DISTANCE 38 -122 41 -74 DISTANCE 0 0 0 0 DISTANCE 91 0 0 0 output 4080 0 ERROR Case 3 (ROUTE: tie by name + capacity exhaustion) input 7 REGISTER node-A 0 0 1 REGISTER node-B 0 0 1 REGISTER node-C 10 10 100 SET_HEALTHY node-C false ROUTE 0 0 ROUTE 0 0 ROUTE 0 0 output OK OK OK OK node-A 0 node-A,node-B node-B 0 node-A,node-B None node-A,node-B Case 4 (ROUTE: no healthy datacenters) input 4 REGISTER dc1 0 0 1 SET_HEALTHY dc1 false ROUTE 0 0 ROUTE 10 10 output OK OK None None Case 5 (DISTANCE boundary values) input 2 DISTANCE -90 -180 90 180 DISTANCE -90 0 -90 0 output 20015 0 Example Input 7 REGISTER us-west 38 -122 100 REGISTER us-east 41 -74 150 REGISTER us-west 50 -100 50 REGISTER invalid-node 91 0 100 REGISTER invalid-cap 0 0 0 SET_HEALTHY us-east false SET_HEALTHY fake-node true Output OK OK ERROR ERROR ERROR OK ERROR