aoc2020 day21.js

(function()
{
  let input = document.querySelector('pre').innerHTML.trim().split('\n');
  
  let alergens = new Set(input.map(line =>
  {
    return line.split('(contains ')[1].replace(')', '').split(', ');
  }).flat());
  
  let allwords = input.reduce((words, line) =>
  {
    let linewords = line.split('(')[0].trim().split(' ');
    return words.concat(linewords);
  },[]);
  
  let guesses = [...alergens].reduce((map, alergen) =>
  {
    let guess = input.reduce((coll, line) => 
    {    
      if(line.includes(alergen))
      {
        let nonsense = line.split('(')[0].trim().split(' ')
        if(coll.length == 0)
        {
          coll = nonsense;
        }
        else
        {
          coll = coll.filter(ingred => nonsense.includes(ingred));
        }
      }
      return coll;
    },[]);
    map.set(alergen, guess);
    return map;
  }, new Map()); 
  
  let flatguesses = [...guesses.values()].flat();
  
  let goodIngred = allwords.filter(word => !flatguesses.includes(word));
  
  return goodIngred;
})()

(function()
{
  let input = document.querySelector('pre').innerHTML.trim().split('\n');
  
  let alergens = new Set(input.map(line =>
  {
    return line.split('(contains ')[1].replace(')', '').split(', ');
  }).flat());
  
  let guesses = [...alergens].reduce((map, alergen) =>
  {
    let guess = input.reduce((coll, line) => 
    {    
      if(line.includes(alergen))
      {
        let nonsense = line.split('(')[0].trim().split(' ')
        if(coll.length == 0)
        {
          coll = nonsense;
        }
        else
        {
          coll = coll.filter(ingred => nonsense.includes(ingred));
        }
      }
      return coll;
    },[]);
    map.set(alergen, guess);
    return map;
  }, new Map()); 
  
  for(let i = 0; i < 3; i++)
  {
    for(let entry of guesses.entries())
    {
      if(entry[1].length == 1)
      {
        let code = entry[1][0];
        for(let oentry of guesses.entries())
        {
          if(oentry[0] == entry[0])
          {
            continue;
          }

          let oindex = oentry[1].indexOf(code);
          if(oindex > -1)
          {
            oentry[1].splice(oindex,1);
          }
        }
      }
    }
  }
  
  return [...guesses.entries()].sort((a, b) => a>b)
                               .map(guess => guess[1][0])
                               .join(',');
  
})()