Taller keycaps: 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
stepsToTaller. For each number inreadings, look to its right. Find the first number that is larger, not equal. Record how many places to the right it is. Record 0 if no larger number is found. Keep the answers in input order. - Count the even numbers in
stepsToTaller. Store the count inevenCount. A number is even when it divides by 2 with no remainder. - Complete
tallerKeycapsEvenKeyCensusso it returnsevenCount. Return it, do not print it.
Example
If readings is [-8, 5, 7, 7, 7], then stepsToTaller is [1, 1, 0, 0, 0] and tallerKeycapsEvenKeyCensus returns 3.
Rules
- 0 counts as an even number.
- If
stepsToTalleris empty, return 0.
Test data
TEST DATA 1: readings is [8, -6, 0, 7, 8].
TEST DATA 2: readings is [5, 5, -1, 5].
Examples
Input: readings = [8,-6,0,7,8] Output: 2
stepsToTaller is [0, 1, 1, 1, 0]. The even numbers are [0, 0]. There are 2, so return 2.
Input: readings = [5,5,-1,5] Output: 3
stepsToTaller is [0, 0, 1, 0]. The even numbers are [0, 0, 0]. There are 3, so return 3.
Input: readings = [] Output: 0
stepsToTaller 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); 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 stepsToTaller 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.