aoc2021_day11_part1.js

(function(inp)
{
  function getNeighbours(x,y,width)
  {
    let deltas = [
        [-1,-1],
        [-1,0],
        [-1,1],
        [0,-1],
        [0,1],
        [1,-1],
        [1,0],
        [1,1]
     ];
      
     let neighbours = [];
        
     for(let delta of deltas)
     {
         let [xd, yd] = delta;
         let nx = xd+x;
         let ny = yd+y;
       
       	 if(nx < 0 || nx >= width || ny < 0 || ny >= width)
         {
           continue;
         }
       
         neighbours.push([nx, ny]);
     }
     return neighbours;
  }
  
  function updateNeightbours(octopusses, currentIndex, alreadyFlashed, width, flashValue)
  {
    let flashcount = 0;
    let x = currentIndex%width;
    let y = Math.floor(currentIndex/width);
    let neighbours = getNeighbours(x,y,width);
    for(let neigh of neighbours)
    {
      let [nx, ny] = neigh;
      let ni = nx + ny*width;
      if(!alreadyFlashed.includes(ni))
      {
        octopusses[ni]++;
        if(octopusses[ni] > flashValue)
        {
          alreadyFlashed.push(ni);
          flashcount++;
          octopusses[ni] = 0;
          flashcount += updateNeightbours(octopusses, ni, alreadyFlashed, width, flashValue);          
        }
      }
    }
    return flashcount;
  }
  
  const width = 10;
  const flashValue = 9;
  
  let octopusses = inp.split('\n').filter(line=>line!='').map(line => line.split('').map(n => parseInt(n, 10))).flat();
  
  let init = '';
  let oi = 0;
  for(let octo of octopusses)
  {
    init += octo.toString();
    if(oi == 9)
    {
      init += '\n';
      oi = 0;
    }
    else
    {
      oi++;
    }
  }
  console.log(init);
  let flashcount = 0;
  
  for(let _ = 0; _ < 100; _++)
  {
    let alreadyflashed = [];
  
    for(let octoIndex = 0; octoIndex < octopusses.length; octoIndex++)
    {
      if(alreadyflashed.includes(octoIndex))
      {
        continue;
      }
      octopusses[octoIndex]++
      if(octopusses[octoIndex] > flashValue)
      {
        octopusses[octoIndex] = 0;
        alreadyflashed.push(octoIndex);
        flashcount++;
        flashcount += updateNeightbours(octopusses, octoIndex, alreadyflashed, width, flashValue);
      }
    }
    let s = '';
    let ri = 0
    for(let octo of octopusses)
    {
      s += octo.toString();
      if(ri == 9)
      {
        s += '\n';
        ri = 0;
      }
      else
      {
        ri++;
      }
    }
    console.log(s);
  }
  return flashcount;
})(document.querySelector('pre').textContent);