CollegeStash

Tag: swe

  • Meeting Rooms II

    Given a list of meetings, that may or may not overlap, calculate the total number of rooms that are required to conduct all the meetings according to the schedule.

    Java

    class Solution {
    public int minMeetingRooms(int[][] intervals) {
        int[] start = new int[intervals.length];
        int[] end = new int[intervals.length];
        for (int i = 0; i < intervals.length; i++) {
            start[i] = intervals[i][0];
            end[i] = intervals[i][1];
        }

        Arrays.sort(start);
        Arrays.sort(end);

        int endPtr = 0, rooms = 0;
        for (int i = 0; i < intervals.length; i++) {
            if (start[i] < end[endPtr]) {
                rooms++;
            } else {
                endPtr++;
            }
        }
        return rooms;
    }
}

    Runtime Complexity: O(nlog(n))

    Space Complexity: O(n)

    Javascript (ES6)

    /**
 * @param {number[][]} intervals
 * @return {number}
 */
const minMeetingRooms = (intervals) => {
  let startList = [];
  let endList = [];
  let endPos = 0;
  let rooms = 0;
  for (const [start, end] of intervals) {
    startList.push(start);
    endList.push(end);
  }
  startList.sort((a, b) => a - b);
  endList.sort((a, b) => a - b);
  for (let i = 0; i < intervals.length; i++) {
    if (startList[i] < endList[endPos]) {
      rooms++;
    } else {
      endPos++;
    }
  }
  return rooms;
};

// console.log(minMeetingRooms([[7, 10],[2, 4]]));
// 1

    Demo

  • Throttling function calls with a Queue in Javascript (ES6)

    The following ES6 Javascript code, helps to throttle function calls without discarding them. It uses a queue to keep track of all the function calls. We can use the reset method to reset the queue and the setTimeout() method.

    const throttle = (fn, delay) => {
  let timeout;
  let noDelay = true;
  let queue = [];
  const start = () => {
    if (queue.length) {
      const {context, args} = queue.shift();
      fn.apply(context, arguments);
      timeout = setTimeout(start, delay);
    } else {
      noDelay = true;
    }
  };

  const ret = (...args) => {
    queue.push({
      context: this,
      args,
    });
    if (noDelay) {
      noDelay = false;
      start();
    }
  };

  ret.reset = () => {
    clearTimeout(timeout);
    queue = [];
  };
  return ret;
};

/* Usage */
const print = (number) => {
  console.log(`Hello World! ${number}`);
}

const test = throttle(print, 3000);

test(1);
test(2);
test(3);

// test.reset(); This will clear the queue and hence the above test case will only output the first line.
// Output:
// Hello World! 1
// Hello World! 2
// Hello World! 3

    Demo