Frequency files: Boss receipt
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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
counts. Count how many times each different number appears inreadings. Sort the different numbers from smallest to largest. Put their counts in that order incounts. For [5, 2, 5], the numbers are 2 and 5, socountsis [1, 2]. - Multiply each number in
countsby its position, counting from 1: the first number by 1, the second by 2, and so on. - Add those products. Store the sum in
weightedTotal. - Complete
frequencyFilesBossReceiptso it returnsweightedTotal. Return it, do not print it.
Example
If readings is [-4, 9, 9, 0, 12], then counts is [1, 1, 2, 1] and frequencyFilesBossReceipt returns 13.
Rules
- If
countsis empty, return 0.
Test data
TEST DATA 1: readings is [-7, 9, 0, 8, 9].
TEST DATA 2: readings is [-8, 9, 9, 9].
Examples
Input: readings = [-7,9,0,8,9] Output: 14
counts is [1, 1, 1, 2]. Multiply by positions that start at 1: 1 * (1) + 2 * (1) + 3 * (1) + 4 * (2) = 14. Return 14.
Input: readings = [-8,9,9,9] Output: 7
counts is [1, 3]. Multiply by positions that start at 1: 1 * (1) + 2 * (3) = 7. Return 7.
Input: readings = [] Output: 0
counts is []. There are no numbers to multiply or add, 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 + d log d); extra memory, including the helper list, O(n). n is the input length; d is the number of different values. These labels describe how work and memory grow with the input.
Practice focus
Build counts 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.