Undo drawer: Threshold file
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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
stack. Use a stack, which is a pile where you add and remove items only at the top. Readreadingsfrom left to right. A number of 0 or more adds that number to the top. A negative number tells you how many top items to remove: -3 means remove up to three items. Stop if the stack becomes empty.stackis the final stack, from bottom to top. - Count the numbers in
stackthat are at leastk(greater than or equal tok). Store the count inatLeastK. - Complete
undoDrawerThresholdFileso it returnsatLeastK. Return it, do not print it.
Example
If readings is [6, 8, -9, 8, 8] and k is 7, then stack is [8, 8] and undoDrawerThresholdFile returns 2.
Rules
- If
stackis empty, the count is 0. 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 [20, 0, 15, -4, 20] and k is 6.
TEST DATA 2: readings is [6, 6, -3, 6] and k is 3.
Examples
Input: readings = [20,0,15,-4,20] k = 6 Output: 1
stack is [20]. Here k is 6. The numbers at least 6 are [20]. There are 1, so return 1.
Input: readings = [6,6,-3,6] k = 3 Output: 1
stack is [6]. Here k is 3. The numbers at least 3 are [6]. There are 1, so return 1.
Input: readings = [] k = 2 Output: 0
stack is []. Here k is 2. The numbers at least 2 are []. There are 0, so return 0.
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 stack 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.