1450. Number of Students Doing Homework at a Given Time

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.

• Example 3:
  Input: startTime = [4], endTime = [4], queryTime = 5
  Output: 0

• Example 4:
  Input: startTime = [1,1,1,1], endTime = [1,3,2,4], queryTime = 7
  Output: 0

• Example 5:
  Input: startTime = [9,8,7,6,5,4,3,2,1], endTime = [10,10,10,10,10,10,10,10,10], queryTime = 5
  Output: 5

var busyStudent = function(startTime, endTime, queryTime) {
    let num = 0;
    for(let p in startTime) {
    	if(startTime[p] <= queryTime && endTime[p] >= queryTime) num += 1;
    }
    return num;
};