aoc-2021/day05/day05.ts

import * as A from "fp-ts/Array";
import * as N from "fp-ts/number";
import * as O from "fp-ts/Option";

import { pipe } from "fp-ts/lib/function";
import { contramap, max, min } from "fp-ts/lib/Ord";
import { Eq, struct } from 'fp-ts/Eq'

import { vectors as testVetctors } from "./input.test";
import { vectors as inputVectors } from "./input";

type Point = { x: number, y: number };
type Vector = { from: Point, to: Point };

const parseVectors = (input: string) => pipe(
    input.split("\n"),
    A.map<string, Vector>(v => {
        const points = pipe(
            v.split(" -> "),
            A.map<string, Point>(p => {
                const coords = pipe(
                    p.split(","),
                    A.map(parseInt)
                );
                return {
                    x: coords[0],
                    y: coords[1]
                };
            })
        );
        return {
            from: points[0],
            to: points[1]
        };
    })
);

const vectors = parseVectors(
    // testVetctors
    inputVectors
);

const maxNum = max(N.Ord);
const minNum = min(N.Ord);

const expand = (vector: Vector): Point[] => pipe(
    vector.from.x === vector.to.x
        ? A.replicate(maxNum(vector.to.y, vector.from.y) - minNum(vector.to.y, vector.from.y) + 1, vector.from.x)
        : A.makeBy(
            maxNum(vector.to.x, vector.from.x) - minNum(vector.to.x, vector.from.x) + 1,
            n => (vector.to.x > vector.from.x ? vector.from.x + n : vector.from.x - n)
        ),
    A.zip(vector.from.y === vector.to.y
        ? A.replicate(maxNum(vector.to.x, vector.from.x) - minNum(vector.to.x, vector.from.x) + 1, vector.from.y)
        : A.makeBy(
            maxNum(vector.to.y, vector.from.y) - minNum(vector.to.y, vector.from.y) + 1,
            n => (vector.to.y > vector.from.y ? vector.from.y + n : vector.from.y - n)
        )),
    A.map(([x, y]) => ({ x, y }))
);

const byX = pipe(N.Ord, contramap((p: Point) => p.x));
const byY = pipe(N.Ord, contramap((p: Point) => p.y));
const eqPoint: Eq<Point> = struct({
    x: N.Eq,
    y: N.Eq
});

const group = (points: Point[]): Point[][] => pipe(
    points,
    A.reduce([] as Point[][], (groupped, p) =>
        pipe(groupped,
             A.last,
             O.chain(A.last),
             O.map(pp => eqPoint.equals(pp, p)),
             O.getOrElse(() => false))
        ? pipe(groupped,
               A.init,
               O.map(is => [...is, pipe(groupped, A.last, O.map(l => [...l, p]), O.getOrElse(() => [p]))]),
               O.getOrElseW(() => pipe(groupped, A.append([p]))))
        : pipe(groupped,
               A.append([p])))
);

const result = pipe(
    vectors,
    // A.filter(v => v.from.x === v.to.x || v.from.y === v.to.y),
    A.map(expand),
    A.flatten,
    A.sortBy([byX, byY]),
    group,
    A.reduce(0, (count, ps) => ps.length > 1 ? count + 1 : count)
);

console.log(result);