advent-of-code-2022/2022/09/solution2.ts

const sample = await Deno.readTextFile("sample.txt");
const input = await Deno.readTextFile("input.txt");

type Direction = "D" | "R" | "L" | "U";
type Vector = { x: number; y: number };
type Step = {
  k0: Vector;
  k1: Vector;
  k2: Vector;
  k3: Vector;
  k4: Vector;
  k5: Vector;
  k6: Vector;
  k7: Vector;
  k8: Vector;
  k9: Vector;
};

const vector = {
  add(vec1: Vector, vec2: Vector): Vector {
    return { x: vec1.x + vec2.x, y: vec1.y + vec2.y };
  },
  distance(vec1: Vector, vec2: Vector): number {
    return Math.sqrt((vec2.x - vec1.x) ** 2 + (vec2.y - vec1.y) ** 2);
  },
  between(vec1: Vector, vec2: Vector): Vector {
    return {
      x: Math.floor((vec1.x + vec2.x) / 2),
      y: Math.floor((vec1.y + vec2.y) / 2),
    };
  },
} as const;

const directions: Record<Direction, Vector> = {
  R: { x: 1, y: 0 },
  D: { x: 0, y: 1 },
  L: { x: -1, y: 0 },
  U: { x: 0, y: -1 },
};

/**** PART 1 ********************************/
function lerp(start: number, end: number, t: number): number {
  return (1 - t) * start + t * end;
}

function mapRange(
  value: number,
  start1: number,
  end1: number,
  start2: number,
  end2: number
): number {
  const t = (value - start1) / (end1 - start1);
  return lerp(start2, end2, t);
}

const print = (width: number, height: number, steps: Step[]): void => {
  const grid = Array.from(new Array(height), () =>
    Array.from(new Array(width), () => ".")
  );

  steps.forEach(({ k9 }) => {
    grid[k9.y][k9.x] = "#";
  });

  for (let y = 0; y < height; y += 1) {
    let line = "";
    for (let x = 0; x < width; x += 1) {
      line += grid[y][x];
    }
    console.log(line);
  }
};

const solvePart1 = (data: string): number | any => {
  const visitedSteps = data
    .split("\n")
    .filter(Boolean)
    .map((line) => line.split(" ") as [string, string])
    .map(([dir, amount]): [Direction, number] => [
      dir as Direction,
      parseFloat(amount),
    ])
    .reduce(
      (steps, [dir, amount]) => {
        for (let i = 0; i < amount; i += 1) {
          const lastStep = steps[steps.length - 1];
          const { k0 } = lastStep;
          const newStep = {
            ...lastStep,
            k0: vector.add(k0, directions[dir]),
          } as Step;
          for (let i = 1; i < 9; i += 1) {
            newStep["k" + i] =
              vector.distance(lastStep["k" + (i - 1)], lastStep["k" + i]) >= 1.5
                ? lastStep["k" + (i - 1)]
                : lastStep["k" + i];
          }
          steps.push(newStep);
        }
        return steps;
      },
      [
        {
          k0: { x: 0, y: 0 },
          k1: { x: 0, y: 0 },
          k2: { x: 0, y: 0 },
          k3: { x: 0, y: 0 },
          k4: { x: 0, y: 0 },
          k5: { x: 0, y: 0 },
          k6: { x: 0, y: 0 },
          k7: { x: 0, y: 0 },
          k8: { x: 0, y: 0 },
          k9: { x: 0, y: 0 },
        },
      ] as Step[]
    );
  console.log("visitedSteps", visitedSteps);

  const widthRange = visitedSteps.reduce(
    ({ min, max }, { h, t }) => {
      const stepMin = h[0] < t[0] ? h[0] : t[0];
      const stepMax = h[0] > t[0] ? h[0] : t[0];
      return {
        min: min < stepMin ? min : stepMin,
        max: max > stepMax ? max : stepMax,
      };
    },
    { min: 0, max: 0 }
  );
  const width = widthRange.max - widthRange.min + 1;

  const heightRange = visitedSteps.reduce(
    ({ min, max }, { h, t }) => {
      const stepMin = h[1] < t[1] ? h[1] : t[1];
      const stepMax = h[1] > t[1] ? h[1] : t[1];
      return {
        min: min < stepMin ? min : stepMin,
        max: max > stepMax ? max : stepMax,
      };
    },
    { min: 0, max: 0 }
  );
  const height = heightRange.max - heightRange.min + 1;

  const normalizedVisistedSteps = visitedSteps.map(({ h, t }) => {
    const yT = Math.round(
      mapRange(t[1], heightRange.min, heightRange.max, 0, height - 1)
    );
    const xT = Math.round(
      mapRange(t[0], widthRange.min, widthRange.max, 0, width - 1)
    );
    const yH = Math.round(
      mapRange(h[1], heightRange.min, heightRange.max, 0, height - 1)
    );
    const xH = Math.round(
      mapRange(h[0], widthRange.min, widthRange.max, 0, width - 1)
    );
    return { h: [yH, xH], t: [yT, xT] } as Step;
  });

  print(width, height, normalizedVisistedSteps);

  return new Set(normalizedVisistedSteps.map(({ t }) => `${t[0]},${t[1]}`))
    .size;
};

console.log("Sample:", solvePart1(sample)); // 13
console.log("Input", solvePart1(input)); // 1851