First arrivals: Peak ticket
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Inputs
readings is a list of integers (numbers with no decimal part). It may be empty, and numbers may repeat unless task 1 says otherwise.
Your tasks
- Create a list
firstCopies. Keep the first copy of each number inreadings. Skip any later copies of the same number. Keep the order in which the numbers first appear. For [4, 2, 4, 3, 2],firstCopiesis [4, 2, 3]. - Find the largest number in
firstCopies. Store it inlargest. - Complete
firstArrivalsPeakTicketso it returnslargest. Return it, do not print it.
Example
If readings is [8, 9, 2, 2, -9], then firstCopies is [8, 9, 2, -9] and firstArrivalsPeakTicket returns 9.
Rules
- If
firstCopiesis empty, return 0. - If every number is negative, return the largest negative number. Do not replace it with 0.
Test data
TEST DATA 1: readings is [8, 0, 8, -4, 11].
TEST DATA 2: readings is [4, 4, 4, -5].
Examples
Input: readings = [8,0,8,-4,11] Output: 11
firstCopies is [8, 0, -4, 11]. The largest number is 11. Return 11.
Input: readings = [4,4,4,-5] Output: 4
firstCopies is [4, -5]. The largest number is 4. Return 4.
Input: readings = [] Output: 0
firstCopies is []. The list is empty, so return 0.
Input limits
- 0 <= input size <= 50000.
- Answers fit in a signed 32-bit integer: -2,147,483,648 through 2,147,483,647.
- Input numbers have no decimal part. They range from -1,000,000 to 1,000,000. Follow any extra input rules in task 1.
Efficiency goal
Big-O describes how the work or memory needed grows as the input gets larger.
Efficiency goal: time O(n); extra memory, including the helper list, O(n). n is the input length. These labels describe how work and memory grow with the input.
Practice focus
Build firstCopies first, then return exactly what the tasks ask for. Follow the order, keep repeated values when the rule says so, and check the empty case.