Rising labels: 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
risingLengths. A subsequence keeps numbers in their original order but may skip some numbers. For each position inreadings, find the longest strictly increasing subsequence that ends at that position. Strictly increasing means each next number must be larger; equal numbers do not count as an increase. Record the length, not the chosen numbers. Put one length per position inrisingLengths. - Count the even numbers in
risingLengths. Store the count inevenCount. A number is even when it divides by 2 with no remainder. - Complete
risingLabelsEvenKeyCensusso it returnsevenCount. Return it, do not print it.
Example
If readings is [5, 5, -8, 0, 2], then risingLengths is [1, 1, 1, 2, 3] and risingLabelsEvenKeyCensus returns 1.
Rules
- If
risingLengthsis empty, return 0.
Test data
TEST DATA 1: readings is [0, -7, 2, 14, 14].
TEST DATA 2: readings is [-9, 2, 2, 2].
Examples
Input: readings = [0,-7,2,14,14] Output: 1
risingLengths is [1, 1, 2, 3, 3]. The even numbers are [2]. There are 1, so return 1.
Input: readings = [-9,2,2,2] Output: 3
risingLengths is [1, 2, 2, 2]. The even numbers are [2, 2, 2]. There are 3, so return 3.
Input: readings = [] Output: 0
risingLengths 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 risingLengths 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.