1450. Number of Students Doing Homework at a Given Time

Problem

Given two integer arrays startTime and endTime and given an integer queryTime.

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

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

  Example 1:

Input: startTime = [1,2,3], endTime = [3,2,7], queryTime = 4
Output: 1
Explanation: We have 3 students where:
The first student started doing homework at time 1 and finished at time 3 and wasn't doing anything at time 4.
The second student started doing homework at time 2 and finished at time 2 and also wasn't doing anything at time 4.
The third student started doing homework at time 3 and finished at time 7 and was the only student doing homework at time 4.

Example 2:

Input: startTime = [4], endTime = [4], queryTime = 4
Output: 1
Explanation: The only student was doing their homework at the queryTime.

  Constraints:

• startTime.length == endTime.length

• 1 <= startTime.length <= 100

• 1 <= startTime[i] <= endTime[i] <= 1000

• 1 <= queryTime <= 1000

Solution (Java)

class Solution {
    public int busyStudent(int[] startTime, int[] endTime, int queryTime) {
        int count = 0;
        for (int i = 0; i < startTime.length; i++) {
            if (startTime[i] <= queryTime && endTime[i] >= queryTime) {
                count++;
            }
        }
        return count;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).