Sorting press: Even-key census
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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
sorted. Sortreadingsfrom smallest to largest using merge sort. To use merge sort, split the list into smaller parts, sort those parts, then join the sorted parts in order. Keep all repeated numbers.sortedis the sorted list. - Count the even numbers in
sorted. Store the count inevenCount. A number is even when it divides by 2 with no remainder. - Complete
sortingPressEvenKeyCensusso it returnsevenCount. Return it, do not print it.
Example
If readings is [3, 4, -1, 7, 4], then sorted is [-1, 3, 4, 4, 7] and sortingPressEvenKeyCensus returns 2.
Rules
- 0 and negative even numbers count too.
- If
sortedis empty, return 0.
Test data
TEST DATA 1: readings is [11, 11, 0, 7, -3].
TEST DATA 2: readings is [8, 8, 8, -3].
Examples
Input: readings = [11,11,0,7,-3] Output: 1
sorted is [-3, 0, 7, 11, 11]. The even numbers are [0]. There are 1, so return 1.
Input: readings = [8,8,8,-3] Output: 3
sorted is [-3, 8, 8, 8]. The even numbers are [8, 8, 8]. There are 3, so return 3.
Input: readings = [] Output: 0
sorted is []. The even numbers are []. There are 0, so return 0.
Input limits
- 0 <= input size <= 64.
- 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 log 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 sorted 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.