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### by Sumit Chourasia | Jun 05, 2020 | Category :coding | Tags : c-sharpआसानleetcodearrayalgorithmडेटा-संरचना #### Number of Students Doing Homework at a Given Time - Array - Easy - LeetCode - मिनी टीवी

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 = , endTime = , queryTime = 4

Output: 1

Explanation: The only student was doing their homework at the queryTime.

Example 3:

Input: startTime = , endTime = , 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

Constraints:

startTime.length == endTime.length

1 <= startTime.length <= 100

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

1 <= queryTime <= 1000

Solution:

``````using System;
using System.Collections.Generic;
using System.Text;

{
public class BusyStudentSoln
{
public int BusyStudent(int[] startTime, int[] endTime, int queryTime)
{
int count = 0;
for (int i = 0; i < startTime.Length; i++)
{
if(startTime[i] <= queryTime && queryTime <= endTime[i])
{
count++;
}
}

return count;
}
}
}
``````

Time Complexity: O(n)

Space Complexity: O(1)

Unit Tests:

``````using LeetCode.AskGif.Easy.Array;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;
using System.Text;

namespace CodingUnitTest.Easy.Array
{
[TestClass]
public class BusyStudentSolnTests
{
[TestMethod]
public void BusyStudentSoln_First()
{
var startTime = new int[] { 1, 2, 3 };
var endTime = new int[] { 3, 2, 7 };
var queryTime = 4;
var output = 1;
var res = new BusyStudentSoln().BusyStudent(startTime, endTime, queryTime);

Assert.AreEqual(res, output);
}

[TestMethod]
public void BusyStudentSoln_Second()
{
var startTime = new int[] { 4 };
var endTime = new int[] { 4 };
var queryTime = 4;
var output = 1;
var res = new BusyStudentSoln().BusyStudent(startTime, endTime, queryTime);

Assert.AreEqual(res, output);
}

[TestMethod]
public void BusyStudentSoln_Third()
{
var startTime = new int[] { 1, 1, 1, 1 };
var endTime = new int[] { 1, 3, 2, 4 };
var queryTime = 7;
var output = 0;
var res = new BusyStudentSoln().BusyStudent(startTime, endTime, queryTime);

Assert.AreEqual(res, output);
}

[TestMethod]
public void BusyStudentSoln_Fourth()
{
var startTime = new int[] { 9, 8, 7, 6, 5, 4, 3, 2, 1 };
var endTime = new int[] { 10, 10, 10, 10, 10, 10, 10, 10, 10 };
var queryTime = 5;
var output = 5;
var res = new BusyStudentSoln().BusyStudent(startTime, endTime, queryTime);

Assert.AreEqual(res, output);
}

[TestMethod]
public void BusyStudentSoln_Fifth()
{
var startTime = new int[] { 4 };
var endTime = new int[] { 4 };
var queryTime = 5;
var output = 0;
var res = new BusyStudentSoln().BusyStudent(startTime, endTime, queryTime);

Assert.AreEqual(res, output);
}
}
}
``````