make this FAST

optmize-me.js

const d3 = require("d3");
const MersenneTwister = require("mersenne-twister");
const generator = new MersenneTwister();

/*
generate random attempts at playing a correct sequence of notes,
given a range of midi (note) and duration options
*/

function generateAttempts({ range, sequence, iterations }) {
  const answer = sequence.map(d => `${d.midi}-${d.duration}.`).join("");
  const { midis, durations } = range;
  midis.sort(d3.ascending);
  durations.sort(d3.ascending);
  const mL = midis.length;
  const dL = durations.length;

  // this is where the magic happens (ie optimization needed)
  const makeAttempt = () => {
    const seq = sequence.map(() => {
      const mR = midis[Math.floor(generator.random() * mL)];
      const dR = durations[Math.floor(generator.random() * dL)];
      return [mR, dR];
    });
    const a = seq.map(d => `${d[0]}-${d[1]}.`).join("");

    done = a === answer;
    return { seq, done };
  };

  const output = [];
  let i = 0;

  while (i < iterations) {
    // store the 1000 most recent attempts
    const a = makeAttempt();
    output[i % 1000] = a;
    if (a.done) break;
    i += 1;
  }

  return { output, done, attempts: i };
}

function init() {
  // INPUT
  const range = { midis: [73, 64, 66, 74], durations: [1, 2, 3] };
  const sequence = [
    { midi: 73, duration: 1 },
    { midi: 64, duration: 2 },
    { midi: 66, duration: 3 },
    { midi: 66, duration: 1 },
    { midi: 74, duration: 2 },
    { midi: 73, duration: 2 },
    { midi: 66, duration: 1 }
  ];
  const iterations = 1000000;

  const result = generateAttempts({ range, sequence, iterations });
}

init();