AoC-2017-day12.js

const input = require("fs").readFileSync("day12-input.txt", "UTF-8");

pairs = {};
input.split("\n").forEach(row => {
  split = row.split(" <-> ");
  split[1] = split[1].split(", ");
  pairs[split[0]] = split[1];
});

count = 0;
seen = [];
program = {};
match = 0;
Object.keys(pairs).forEach(key => (program[key] = 0));

function group() {
  Object.keys(pairs).forEach(key => {
    if (key === match) {
      program[key] = 1;
      seen.push(key);
    }
    seen = [];
    if (find(pairs[key]) > 0) {
      program[key] = 1;
    }
  });
}

function find(childern) {
  c = 0;
  childern.forEach(child => {
    if (child == match) {
      c++;
    }
    if (seen.indexOf(child) === -1) {
      seen.push(child);
      c += find(pairs[child]);
    }
  });
  return c;
}

function reduceHash() {
  matched = Object.keys(program).filter(key => program[key] === 1);
  matched.forEach(id => {
    delete pairs[id];
    delete program[id];
  });
}

group();
groups = 1;
reduceHash();

console.log("Part 1:", matched.length);

while (Object.keys(program).length) {
  match = Object.keys(program).filter(key => program[key] === 0)[0];
  group();
  groups++;
  reduceHash();
}

console.log("Part 2:", groups);