Window pegs: Even-key census
Stuck or curious how this works? Visualize Stack Operations ↗
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
windowMaxes. Take every group of exactlyknumbers next to each other inreadings. Move the group one place right each time. Record the largest number in each group, from left to right. Ifkis larger than the input length,windowMaxesis empty. - Count the even numbers in
windowMaxes. Store the count inevenCount. A number is even when it divides by 2 with no remainder. - Complete
windowPegsEvenKeyCensusso it returnsevenCount. Return it, do not print it.
Example
If readings is [6, 6, -9, 4, 8] and k is 1, then windowMaxes is [6, 6, -9, 4, 8] and windowPegsEvenKeyCensus returns 4.
Rules
- If
windowMaxesis empty, return 0. k(a whole number from 1 to 8) is the window size in task 1.
Test data
TEST DATA 1: readings is [-10, 16, 3, 3, 0] and k is 2.
TEST DATA 2: readings is [7, -6, 7, 7] and k is 7.
Examples
Input: readings = [-10,16,3,3,0] k = 2 Output: 2
windowMaxes is [16, 16, 3, 3]. The even numbers are [16, 16]. There are 2, so return 2.
Input: readings = [7,-6,7,7] k = 7 Output: 0
windowMaxes is []. The even numbers are []. There are 0, so return 0.
Input: readings = [] k = 8 Output: 0
windowMaxes is []. The even numbers are []. There are 0, so return 0.
Input limits
- 0 <= input size <= 64.
- k is a whole number from 1 to 8. 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 windowMaxes 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.