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Design Underground System

MediumArrays

Build a system with checkIn(id, station, t), checkOut(id, station, t), and getAverageTime(start, end) returning the average travel time of all trips from start to end so far.

Input format (stdin): the first line has q. Each line is 'in id station t', 'out id station t', or 'avg start end'. For each avg, print the average with one decimal place.

Examples
Input: 5 in 1 A 3 out 1 B 8 in 2 A 10 out 2 B 15 avg A B
Output: 5.0
Two trips A->B took 5 each, average 5.0.
Constraints
  • 1 <= q <= 10^4
  • times are non-negative integers
Sheets
NeetCode 250
design-underground-system.cpp1 sample tests
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Custom input (stdin)
Output

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