aoc2021_day3_part2.js

(function(inp)
{
  let oxbits = '';
  let co2bits = '';
  
  const width = 12;
  let lineinp = inp.replaceAll('\n', '');
  let lines = inp.split('\n');
  
  for(let x = 0; x < width; x++)
  {
    let ones = 0;
    let zeros = 0;
    
    for(let index = x; index < lineinp.length; index += width)
    {
			if(lineinp[index] == '1')
      {
        ones++;
      }
      else
      {
        zeros++;
      }
    }
    
    if(ones >= zeros)
    {
      oxbits += '1';
    }
    else
    {
      oxbits += '0';
    }
    
    lines = lines.filter(line => line.startsWith(oxbits));
    
    if(lines.length == 1)
    {
      oxbits = lines[0];
      break;
    }
    
    lineinp = lines.join('');
  }
   
  lineinp = inp.replaceAll('\n', '');
  lines = inp.split('\n');
  
  for(let x = 0; x < width; x++)
  {
    let ones = 0;
    let zeros = 0;
    
    for(let index = x; index < lineinp.length; index += width)
    {
			if(lineinp[index] == '1')
      {
        ones++;
      }
      else if(lineinp[index] == '0')
      {
        zeros++;
      }
    }
    
    if(zeros > ones)
    {
      co2bits += '1';
    }
    else
    {
      co2bits += '0';
    }
    
    lines = lines.filter(line => line.startsWith(co2bits));
    
    if(lines.length == 1)
    {
      co2bits = lines[0];
      break;
    }
    
    lineinp = lines.join('');
  }
  
  let ox = parseInt(oxbits, 2);
  let co2 = parseInt(co2bits, 2);
  
	return ox*co2;
})(document.querySelector('pre').innerHTML);