Electromagnetic Moat - Advent of Code - 20171224

ac20171224.js

const ports = require('./ports');

let findCompatiblePorts = function(currentPort, portSize, ports, usedPorts) {
  ports = ports
    .filter(p => p !== currentPort)
    .filter(p => usedPorts.indexOf(p) == -1)
    .filter(port => {
      let [a, b] = port.split('/');
      return a == portSize || b == portSize ? true : false;
    });
  return ports;
};

let strongestBridge = function(port, portSize, ports, usedPorts, strength) {
  usedPorts = usedPorts.slice();
  let nextPorts = findCompatiblePorts(port, portSize, ports, usedPorts);
  /*
  console.log(
    'strongestBridge',
    port,
    portSize,
    strength);
*/
  if (nextPorts.length == 0) {
    return strength;
  } else {
    let strongest = strength;
    nextPorts.forEach(p => {
      let [portA, portB] = p.split('/');
      let newPortSize = portSize !== portA ? portA : portB;
      let newStrength = strongestBridge(
        p,
        newPortSize,
        ports,
        [port, ...usedPorts],
        strength + parseInt(portA) + parseInt(portB)
      );
      strongest = newStrength > strongest ? newStrength : strongest;
    });
    return strongest;
  }
};

let bridgeSize = [];
let longestBridge = function(port, portSize, ports, usedPorts, length) {
  usedPorts = usedPorts.slice();
  let nextPorts = findCompatiblePorts(port, portSize, ports, usedPorts);

/*
  console.log(
    'longestBridge',
    port,
    portSize,
    length,
  usedPorts, nextPorts);
*/

  if (nextPorts.length == 0) {
    if (bridgeSize[length] == undefined) {
      bridgeSize[length] = [[port, ...usedPorts]];
    } else {
      bridgeSize[length].push([port, ...usedPorts]);
    }
    return length;
  } else {
    let longest = length;
    nextPorts.forEach(p => {
      let [portA, portB] = p.split('/');
      let newPortSize = portSize !== portA ? portA : portB;
      let newLength = longestBridge(
        p,
        newPortSize,
        ports,
        [port, ...usedPorts],
        length + 1
      );
      longest = newLength > longest ? newLength : longest;
    });
    return longest;
  }
};

let buildBridge_1 = function(ports) {
  let portSize = '0';
  let startPorts = findCompatiblePorts('0/0', portSize, ports, []);
  let strongest = 0;
  let longest = 0;

  startPorts.forEach(p => {
    let [portA, portB] = p.split('/');
    let newPortSize = portSize !== portA ? portA : portB;
    let strength = strongestBridge(
      p,
      newPortSize,
      ports,
      [p],
      parseInt(portA) + parseInt(portB)
    );
    strongest = strongest > strength ? strongest : strength;
  });

  return strongest;
};

let buildBridge_2 = function(ports) {
  let portSize = '0';
  let startPorts = findCompatiblePorts('0/0', portSize, ports, []);
  let strongest = 0;
  let longest = 0;

  startPorts.forEach(p => {
    let [portA, portB] = p.split('/');
    let newPortSize = portSize !== portA ? portA : portB;
    let length = longestBridge(
      p,
      newPortSize,
      ports,
      [],
      1
    );
    longest = longest > length ? longest : length;
  });

  console.log(bridgeSize[longest]);

  return bridgeSize[longest].reduce((acc, chain) => {
    let strength = chain.reduce((acc, link) => {
      let [portA, portB] = link.split('/');
      acc += parseInt(portA) + parseInt(portB);
      return acc;
    }, 0);

    return acc > strength ? acc : strength;
  }, 0);
};

let buildBridge = buildBridge_2;

let result = buildBridge(ports);
console.log(result);