HiCal interviewcake question

q.js

const merger = meetings => {
  // initialize merged blocks with first meeting
  let merged = [meetings[0]];
  for (let mtg = 1; mtg < meetings.length; mtg++) {
    // iterate over each other meeting once
    // otherwise, look for collision btwn current mtg and existing time blocks
    let collisionIndex = -1;
    for(let i = 0; i < merged.length; i++){
      // iterate over each existing merged block
      if (
        meetings[mtg].startTime <= merged[i].endTime && 
        meetings[mtg].endTime >= merged[i].startTime
      ){
        // Collision between mtg and block! 
        // Expand block: start at the earlier of mtg's startTime or block's startTime
        merged[i].startTime = Math.min(merged[i].startTime, meetings[mtg].startTime);
        // Expand block: end at the later of mtg's endTime or block's endTime
        merged[i].endTime = Math.max(merged[i].endTime, meetings[mtg].endTime);
        if(collisionIndex < 0) {
          // track where collision was in case of future collisions
          collisionIndex = i;
        } else {
          /*
          this is not the first block this meeting has colided with! That means merged[i] collides with merged[collisionIndex], so...
          -- expand merged[collisionIndex] 
          -- and merged.pop() to discard merged[i]
          */
          merged[collisionIndex].startTime = Math.min(merged[i].startTime, merged[collisionIndex].startTime);
          merged[collisionIndex].endTime = Math.max(merged[i].endTime,  merged[collisionIndex].endTime);
          merged.pop()
        }
      }

    }
    if(collisionIndex < 0) {
      // this meeting never colided, so it becomes a new block
      merged.push(meetings[mtg])
    }
  }
  return merged
}


const test = (arr) => {
  console.log("Testing...")
  console.log(arr)
  const mergedMeetings = merger(arr)
  console.log("final result:")
  console.log(mergedMeetings)
}
test([
    { startTime: 0,  endTime: 1 },
    { startTime: 3,  endTime: 5 },
    { startTime: 4,  endTime: 8 },
    { startTime: 10, endTime: 12 },
    { startTime: 9,  endTime: 10 },
  ]);

  test([
    { startTime: 0,  endTime: 1 },
    { startTime: 3,  endTime: 5 },
    { startTime: 4,  endTime: 8 },
    { startTime: 10, endTime: 12 },
    { startTime: 9,  endTime: 10 },
    { startTime: 8,  endTime: 9 }
  ]);
/*
Your company built an in-house calendar tool called HiCal. You want to add a feature to see the times in a day when everyone is
available.
To do this, you’ll need to know when any team is having a meeting. In HiCal, meetings are stored as objects with integer
properties startTime and endTime. These integers represent the number of 30-minute blocks past 9:00am.
For example:
{ startTime: 2, endTime: 3 }  // meeting from 10:00 – 10:30 am
{ startTime: 6, endTime: 9 }  // meeting from 12:00 – 1:30 pm
Write a function mergeRanges() that takes an array of multiple meeting time ranges and returns an array of condensed ranges.
For example, given:
[
  { startTime: 0,  endTime: 1 },
  { startTime: 3,  endTime: 5 },
  { startTime: 4,  endTime: 8 },
  { startTime: 10, endTime: 12 },
  { startTime: 9,  endTime: 10 },
]
your function would return:
[
  { startTime: 0, endTime: 1 },
  { startTime: 3, endTime: 8 },
  { startTime: 9, endTime: 12 },
]
*/