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Implement Hit Counter

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Problem statement

Process chronological hit and getHits operations. A query returns the number of hits in the inclusive interval from timestamp - 299 through timestamp. Return "null" for a hit and the decimal count for a query.

Function

runHitCounter(operations: String[], timestamps: int[]) → String[]

Examples

Example 1

operations = ["hit","hit","hit","getHits","hit","getHits"]timestamps = [1,2,3,4,300,301]return = ["null","null","null","3","null","3"]

At time 301, the hit at time 1 has expired but the other three remain.

Constraints

  • Operation and timestamp arrays have equal non-zero length.
  • Timestamps are positive and non-decreasing.
  • There are at most 100000 operations.

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public String[] runHitCounter(String[] operations, int[] timestamps) {
  // Write your code here.
}
operations["hit","hit","hit","getHits","hit","getHits"]
timestamps[1,2,3,4,300,301]
expected["null", "null", "null", "3", "null", "3"]
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