text: const classroomLecture = (input) => {
    // Base case
    if(input.length === 0 || input === null) return 0;
  
    const startingTimes = [];
    const endingTimes = [];
  
    for (let i = 0; i < input.length; i++) {
      const [startTime, endTime] = input[i];
  
      startingTimes[i] = startTime;
      endingTimes[i] = endTime;
    }
  
    // Sort into increasing order
    startingTimes.sort((a,b) => a - b);
    endingTimes.sort((a,b) => a - b);
  
  	let maxClassrooms = 0;
    let currClassrooms = 0;
  
    // Seperate iterators
    let sIndex = 0;
    let eIndex = 0;
  
    while(sIndex < startingTimes.length || eIndex < endingTimes.length) {
    	if(sIndex > startingTimes.length) break;
  
      if (startingTimes[sIndex] < endingTimes[eIndex]) {
      	// Move starting index times
      	currClassrooms++;
        sIndex++;
      } else {
      	currClassrooms--;
        eIndex++;
      }
      // Take max value
      maxClassrooms = Math.max(maxClassrooms, currClassrooms);
    }
    return maxClassrooms;
  }
  
  console.log(classroomLecture([[30, 75], [0, 50], [60, 150]]));	// 2
  console.log(classroomLecture([[30, 75], [0, 50], [10, 60], [60,150]])); // 3
  console.log(classroomLecture([[30, 75]]));	// 1
  console.log(classroomLecture([[0, 50], [50, 60]]));	// 1
  