algoadvance

You are given two integer arrays startTime and endTime, and an integer queryTime.

The i-th student started doing their homework at the time startTime[i] and finished it at endTime[i].

Return the number of students doing their homework at queryTime. More formally, return the number of students where queryTime lays in the interval [startTime[i], endTime[i]] inclusive.

Example

Example 1:

Input: startTime = [1,2,3], endTime = [3,2,7], queryTime = 4
Output: 1
Explanation: One student was doing their homework at the queryTime.

Example 2:

Input: startTime = [4], endTime = [4], queryTime = 4
Output: 1

Constraints:

1. startTime.length == endTime.length
2. 1 <= startTime.length <= 100
3. 1 <= startTime[i] <= endTime[i] <= 1000
4. 1 <= queryTime <= 1000

Clarifying Questions

1. Are we guaranteed that the startTime and endTime lists are of the same length?
   • Yes, based on the constraints.
2. Is the queryTime guaranteed to fall within the range from 1 to 1000?
   • Yes.

Strategy

• We need to iterate through each student’s start and end times and check if queryTime lies between startTime[i] and endTime[i] inclusive.
• If queryTime is within the range [startTime[i], endTime[i]], we increment our count.
• Finally, return the count.

Code

def busyStudent(startTime, endTime, queryTime):
    count = 0
    for i in range(len(startTime)):
        if startTime[i] <= queryTime <= endTime[i]:
            count += 1
    return count

Time Complexity

• The time complexity of this solution is O(n) where n is the length of the startTime list because we are iterating through all students once.
• Since the length of startTime is at most 100, this solution is efficient.

Test Cases

1. Test Case 1:

   startTime = [1,2,3]
   endTime = [3,2,7]
   queryTime = 4
   Output: 1
   

2. Test Case 2:

   startTime = [4]
   endTime = [4]
   queryTime = 4
   Output: 1
   

3. Test Case 3:

   startTime = [1,1,1,1,1]
   endTime = [10,10,10,10,10]
   queryTime = 5
   Output: 5
   

4. Test Case 4:

   startTime = [1,2,3,4,5]
   endTime = [5,5,5,5,5]
   queryTime = 5
   Output: 5
   

5. Test Case 5:

   startTime = [1,2,3,4,5]
   endTime = [5,6,7,8,9]
   queryTime = 1
   Output: 1
   

We can now confidently proceed to check the implementation through these test cases and validate its correctness.

Try our interview co-pilot at AlgoAdvance.com

• Got blindsided by a question you didn’t expect?

• Spend too much time studying?

• Or simply don’t have the time to go over all 3000 questions?