pip is Python’s package manager.

import { AdventOfCodeSolutionFunction } from "./solutions";
import { Grid } from "./utils/grids";
import { LinkedPoint } from "./utils/structures/linkedPoint";
import { makeGridFromMultilineString, SumArray } from "./utils/utils";

class TrailPoint extends LinkedPoint<number, TrailPoint> {
    constructor(x: number, y: number, item: number, grid: Grid<TrailPoint>) {
        super(x, y, item, grid);
    }

    lookAroundValid(): Array<TrailPoint> {
        return this.lookAround().filter(v => v.item == this.item + 1);
    }

    findAllValidPeaks(): Array<TrailPoint> {
        if (this.item == 9)
            return [this];

        // filter for distinct references (this theoretically saves time)
        return [...(new Set(this.lookAroundValid().flatMap(v => v.findAllValidPeaks())))];
    }

    findAllValidPeaksWithReps(): Array<TrailPoint> {
        if (this.item == 9)
            return [this];

        // don't filter
        return this.lookAroundValid().flatMap(v => v.findAllValidPeaksWithReps());
    }
}

export const solution_10: AdventOfCodeSolutionFunction = (input) => {
    const map: Grid<TrailPoint> =
        makeGridFromMultilineString(input)
            .map((row) => row.map((item) => item != "." ? Number(item) : -1))
            .map((row, y) => row.map((item, x) => new TrailPoint(x, y, item, undefined!)));

    map.flat().forEach((v) => v.grid = map); // promise is a promise

    const startNodes: Array<TrailPoint> = map.flat().filter(v => v.item == 0);

    const part_1 = SumArray(startNodes.map(v => v.findAllValidPeaks().length));
    const part_2 = SumArray(startNodes.map(v => v.findAllValidPeaksWithReps().length));

    return {
        part_1, // 557
        part_2, // 1062
    }
}

Full code here.

import { AdventOfCodeSolutionFunction } from "./solutions";
import { MakeEmptyGenericArray } from "./utils/utils";

const pretty_print = (disk: Array<number>) => disk.reduce<string>((prev, curr) => prev + (curr == -1 ? "." : curr), "");
const checksum = (disk: Array<number>) => disk.reduce<number>((prev, curr, index) => prev + (curr == -1 ? 0 : curr * index), 0);

const findSlice = (disk: Array<number>, id: number, startFrom?: number) => {
    const sectionStart = disk.indexOf(id, startFrom);

    if (sectionStart == -1)
        return [-1, -1];

    let sectionEnd = sectionStart;

    while (disk.length > ++sectionEnd && disk[sectionEnd] == id);

    return [sectionStart, sectionEnd];
}

export const solution_9: AdventOfCodeSolutionFunction = (input) => {
    let isFile = false;
    let id = 0;

    // make the disk
    const disk = input.split("").flatMap((v) => {
        isFile = !isFile;
        const count = Number(v);

        if (isFile) {
            id++;
            return MakeEmptyGenericArray(count, () => id - 1);
        }

        return MakeEmptyGenericArray(count, () => -1);
    });

    // make a copy of the disk
    const fragmentedDisk = [...disk];

    // start moving elements on the disk
    let start = 0
    let end = fragmentedDisk.length - 1;
    while (start < end) {
        if (fragmentedDisk[start] != -1) {
            start++;
            continue;
        }

        if (fragmentedDisk[end] == -1) {
            end--;
            continue;
        }

        // swap the values
        fragmentedDisk[start] = fragmentedDisk[end]
        fragmentedDisk[end] = -1;

        start++;
        end--;
    }


    main: while (id-- > 0) {
        // find the section that has the file
        const [sectionStart, sectionEnd] = findSlice(disk, id); // this will never return -1
        const sectionLength = sectionEnd - sectionStart;

        // find any section that can fit the file
        let freeStart;
        let freeEnd = 0;
        do {
            [freeStart, freeEnd] = findSlice(disk, -1, freeEnd);

            // can't find any free spaces or too far right
            if (freeStart == -1 || freeStart > sectionStart)
                continue main;

        } while (freeEnd - freeStart < sectionLength);

        // switch places
        let i = 0;
        while(sectionStart + i < sectionEnd) {
            disk[freeStart + i] = id;
            disk[sectionStart + i++] = -1;
        }
    }


    // calculate the checksums
    return {
        part_1: checksum(fragmentedDisk),
        part_2: checksum(disk),
    }
}