How should I practice Marathon Checkpoint Leaderboard?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Bloomberg LP onsite interview problems in FastPrep.

Is Marathon Checkpoint Leaderboard associated with Bloomberg LP?

FastPrep tags this as a Bloomberg LP onsite interview coding practice problem when the problem catalog has that company and stage context.

Marathon Checkpoint Leaderboard

Bloomberg LP● MediumNEW GRADONSITE INTERVIEW

Learn

Problem statement

Maintain a live leaderboard for a marathon with sensorCount checkpoints numbered from 0 to sensorCount - 1 and playerCount runners numbered from 0 to playerCount - 1.

Before the first operation every runner is at checkpoint -1, ordered by runner ID. Process the operations in order:

["PASS", player, sensor] records that player reached their next checkpoint. Therefore sensor must be exactly one greater than that runner's current checkpoint. Among runners at the same checkpoint, the runner who reached it earlier ranks first.
["TOP", k] requests the first k runners, ranked by larger checkpoint first and then by arrival order at that checkpoint.

For each TOP operation, return one row containing entries of the form "player|checkpoint". Return query rows in encounter order.

Function

marathonLeaderboard(sensorCount: int, playerCount: int, operations: String[][]) → String[][]

Examples

Example 1

sensorCount = 3playerCount = 4operations = [["PASS","2","0"],["PASS","0","0"],["TOP","4"],["PASS","0","1"],["TOP","3"]]return = [["2|0","0|0","1|-1","3|-1"],["0|1","2|0","1|-1"]]

Runner 2 reaches checkpoint 0 before runner 0. After runner 0 advances to checkpoint 1, runner 0 leads.

Example 2

sensorCount = 2playerCount = 3operations = [["TOP","2"],["PASS","1","0"],["PASS","2","0"],["PASS","1","1"],["TOP","3"]]return = [["0|-1","1|-1"],["1|1","2|0","0|-1"]]

The initial order is runner ID order. Later, runner 1 has progressed farther than runners 2 and 0.

Example 3

sensorCount = 1playerCount = 2operations = [["PASS","1","0"],["PASS","0","0"],["TOP","1"]]return = [["1|0"]]

Both runners have reached the finish sensor, and runner 1 arrived first.

Constraints

1 <= sensorCount, playerCount <= 100000.
1 <= operations.length <= 100000.
Every operation is PASS or TOP.
Each PASS uses a valid runner and that runner's next checkpoint.
1 <= k <= playerCount for every TOP.
At least one TOP operation is present.