Ribbon totals: Boss receipt
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
runningTotals. Start a total at 0. Readreadingsfrom left to right. Add each number to the total, then put the new total inrunningTotals. For [2, 3, -1],runningTotalsis [2, 5, 4]. - Multiply each number in
runningTotalsby 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
ribbonTotalsBossReceiptso it returnsweightedTotal. Return it, do not print it.
Example
If readings is [4, 4, -8, 8, 8], then runningTotals is [4, 8, 0, 8, 16] and ribbonTotalsBossReceipt returns 132.
Rules
- If
runningTotalsis empty, return 0.
Test data
TEST DATA 1: readings is [6, 2, -5, 2, 0].
TEST DATA 2: readings is [2, -2, 2, 2].
Examples
Input: readings = [6,2,-5,2,0] Output: 76
runningTotals is [6, 8, 3, 5, 5]. Multiply by positions that start at 1: 1 * (6) + 2 * (8) + 3 * (3) + 4 * (5) + 5 * (5) = 76. Return 76.
Input: readings = [2,-2,2,2] Output: 24
runningTotals is [2, 0, 2, 4]. Multiply by positions that start at 1: 1 * (2) + 2 * (0) + 3 * (2) + 4 * (4) = 24. Return 24.
Input: readings = [] Output: 0
runningTotals 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); 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 runningTotals 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.