aoc2020 day7.js

function shinyGoldContainersp1()
{ 
  const input = document.querySelector('pre').innerHTML;

  const containers = input.match(/(\w+ \w+) bags contain (?:(?:\d+ (\w+ \w+)) bag(?:s?)[.,](?: ?))+/g);
  
  let bags = new Set([]);
  
  let checkedBags = new Set([]);
  
  let newBags = findHoldersFor(containers, 'shiny gold');
  
  checkedBags.add('shiny gold');
  let lastSize = 0;
  
  while(lastSize != checkedBags.size)
  {
    lastSize = checkedBags.size;
    newBags.forEach(bag => 
    {
      bags.add(bag);
    });
    
    let next = [];
    
    while(newBags.length > 0)
    {
      let bag = newBags.pop();
      next = next.concat(findHoldersFor(containers, bag));
      checkedBags.add(bag);
    }
    
    newBags = next;
  }
  
  function findHoldersFor(containers, bagDesc)
  {
    return containers.map(container =>
    {
      let bagMatch = container.match(new RegExp(`(\\w+ \\w+) bags contain .*(?:(?:\\d+ ${bagDesc}) bag(?:s?)[.,](?: ?)).*`));
      return (bagMatch??[])[1]??'';
    }).filter(b => b != '');
  }
  
  return bags.size;
}
              

function shinyGoldContainersp2()
{
  let input = document.querySelector('pre').innerHTML.trim();
  let result = 0;
  
  let bagNodes = new Map();
  
  let ends = input.matchAll(/(\w+ \w+) bags contain no other bags\./g);
  
  [...ends].forEach(bag =>
  {
    let n = new node(bag[1], []);
    bagNodes.set(bag[1], n);
  });
  
  let rules = input.split('\n').filter(line => !line.endsWith('other bags.'));
  
  rules.forEach(rule =>
  {
    let halves = rule.split(' bags contain ');
    let bag = halves[0];
    let curnode = bagNodes.has(bag)?bagNodes.get(bag):(new node(bag, []));
    if(!bagNodes.has(bag))
    {
      bagNodes.set(bag, curnode);
    }
    
    let parts = [...halves[1].matchAll(/(?:(?<count>\d+) (?<colour>\w+ \w+))/g)];

    parts.forEach(part =>
    {
      let colour = part.groups.colour;
      let count = parseInt(part.groups.count, 10);
      let newNode;
      if(!bagNodes.has(colour))
      {
        newnode = new node(colour, []);
        bagNodes.set(colour, newnode);
      }
      else
      {
        newnode = bagNodes.get(colour);
      }
      
      for(let i = 0; i < count; i++)
      {
        curnode.nextbags.push(newnode);
      }
    });
    
  });
  
  return bagNodes.get('shiny gold').containsCount();
}

function node(bag, nextbags)
{
  this.bag = bag;
  this.nextbags = nextbags;
}

node.prototype.containsCount = function()
{
  let count = this.nextbags.length;
  
  count += this.nextbags.reduce((sum, bag) => sum + bag.containsCount(), 0);
  
  return count;
}