Xor register: First qualifying slip
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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
xorValues. Start a stored number at 0. Readreadingsfrom left to right. Combine the stored number and the next number with bitwise XOR. XOR compares their binary digits: matching digits give 0, and different digits give 1. Use leading zeros when needed. For example, 3 XOR 5 is 6 because 011 XOR 101 gives 110. Record the stored number after each update. - Read
xorValuesfrom left to right. Find the first number that is at leastkand store that number, not its position, infirstMatch. - Complete
xorRegisterFirstQualifyingSlipso it returnsfirstMatch. Return it, do not print it.
Example
If readings is [4, 4, 5, 5, 3] and k is 3, then xorValues is [4, 0, 5, 0, 3] and xorRegisterFirstQualifyingSlip returns 4.
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 [0, 7, 3, 3, 9] and k is 3.
TEST DATA 2: readings is [4, 9, 9, 9] and k is 2.
Examples
Input: readings = [0,7,3,3,9] k = 3 Output: 7
xorValues is [0, 7, 4, 7, 14]. Here k is 3. The first number at least 3 is 7. Return that value.
Input: readings = [4,9,9,9] k = 2 Output: 4
xorValues is [4, 13, 4, 13]. Here k is 2. The first number at least 2 is 4. Return that value.
Input: readings = [] k = 8 Output: -1
xorValues is []. Here k is 8. No number is at least 8, 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 are whole numbers from 0 through 20.
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 xorValues 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.