Taller keycaps: First qualifying slip
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
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. - Read
stepsToTallerfrom left to right. Find the first number that is at leastkand store that number, not its position, infirstMatch. - Complete
tallerKeycapsFirstQualifyingSlipso it returnsfirstMatch. Return it, do not print it.
Example
If readings is [7, 9, 2, -6, 2] and k is 8, then stepsToTaller is [1, 0, 0, 1, 0] and tallerKeycapsFirstQualifyingSlip returns -1.
Rules
- If no number is at least
k, return -1. k(a whole number from 1 to 8) is the threshold in task 2: compare each number with it.
Test data
TEST DATA 1: readings is [9, -11, 0, 20, 20] and k is 1.
TEST DATA 2: readings is [4, 4, 4, -3] and k is 4.
Examples
Input: readings = [9,-11,0,20,20] k = 1 Output: 3
stepsToTaller is [3, 1, 1, 0, 0]. Here k is 1. The first number at least 1 is 3. Return that value.
Input: readings = [4,4,4,-3] k = 4 Output: -1
stepsToTaller is [0, 0, 0, 0]. Here k is 4. No number is at least 4, so return -1.
Input: readings = [] k = 2 Output: -1
stepsToTaller is []. Here k is 2. No number is at least 2, so return -1.
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 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.