const input = require('fs').readFileSync('input-day9.txt', 'utf-8');

/** @type {Array<[number, number]} */
const points = input.split("\n").map(r => r.split(',').map(v => parseInt(v, 10)));

let largest = 0;
let largestInside = 0;
for (const [startX, startY] of points) {
    for (const [nextX, nextY] of points) {
        if (startX === nextX && startY === nextY) continue;

        const minX = Math.min(startX, nextX);
        const maxX = Math.max(startX, nextX);
        const minY = Math.min(startY, nextY);
        const maxY = Math.max(startY, nextY);

        const area = (maxX - minX + 1) * (maxY - minY + 1);
        if (area > largest) {
            largest = area;
        }

        if (area <= largestInside) continue;

        // center point check, ala https://en.wikipedia.org/wiki/Even%E2%80%93odd_rule
        const centerX = (minX + maxX) / 2;
        const centerY = (minY + maxY) / 2;
        let inside = false;
        for (const [i, [aX, aY]] of points.entries()) {
            const [bX, bY] = points[i - 1] ?? points[points.length - 1];
            if (centerX === aX && centerY === aY) {
                inside = true;
                break;
            }
            if ((aY > centerY) !== (bY > centerY)) {
                const slope = (centerX - aX) * (bY - aY) - (bX - aX) * (centerY - aY);
                if (slope === 0) {
                    inside = true;
                    break;
                }
                if ((slope < 0) !== (bY < aY)) {
                    inside = !inside;
                }
            }
        }

        if (!inside) continue;

        // check for edge intersections, ala https://en.wikipedia.org/wiki/Line%E2%80%93line_intersection
        let intersects = false;
        for (const [i, [aX, aY]] of points.entries()) {
            const [bX, bY] = points[i - 1] ?? points[points.length - 1];

            if (aX === bX) {
                if (aX > minX && aX < maxX) {
                    const wallMinY = Math.min(aY, bY);
                    const wallMaxY = Math.max(aY, bY);

                    if (Math.max(minY, wallMinY) < Math.min(maxY, wallMaxY)) {
                        intersects = true;
                        break;
                    }
                }
            } else if (aY === bY) {
                if (aY > minY && aY < maxY) {
                    const wallMinX = Math.min(aX, bX);
                    const wallMaxX = Math.max(aX, bX);

                    if (Math.max(minX, wallMinX) < Math.min(maxX, wallMaxX)) {
                        intersects = true;
                        break;
                    }
                }
            }
        }

        if (intersects) continue;

        if (area > largestInside) {
            largestInside = area;
        }
    }
}

console.log(`Part 1 Answer: ${largest}`);
console.log(`Part 2 Answer: ${largestInside}`);

const input = require('fs').readFileSync('input-day5.txt', 'utf-8');

/** @typedef {[number, number]} Range */

/** @type {[Range[], number[]]} */
const [freshRanges, availableIngredients] = input.split("\n\n").map(l => l.split("\n")).map((l, i) => (i === 1) ? l.map(v => parseInt(v, 10)) : l.map(v => v.split('-').map(vv => parseInt(vv, 10))));


let freshOnHand = 0;

for (const ingredient of availableIngredients) {
    for (const [start, stop] of freshRanges) {
        if (ingredient >= start && ingredient <= stop) {
            freshOnHand += 1;
            break;
        }
    }
}

console.log(`Part 1 Answer: ${freshOnHand}`);

const sortedRanges = [...freshRanges].sort((a, b) => a[0] - b[0]);

const mergedRanges = [];
let current = sortedRanges[0];

for (let i = 1; i < sortedRanges.length; i++) {
    const [nextStart, nextEnd] = sortedRanges[i];
    
    if (nextStart <= current[1] + 1) {
        current = [current[0], Math.max(current[1], nextEnd)];
    } else {
        mergedRanges.push(current);
        current = [nextStart, nextEnd];
    }
}

mergedRanges.push(current);

const freshIngredientCount = mergedRanges.reduce((acc, [start, stop]) => acc + ((stop + 1) - start), 0)

console.log(`Part 2 Answer: ${freshIngredientCount}`);

const input = require('fs').readFileSync('input-day4.txt', 'utf-8');

class PrintingDepartmentMap {
    /** @param {string} input */
    constructor(input) {
        /** @type {number[][]} */
        this.map = input.split("\n").map(r => r.split('').map(v => v === '@' ? 1 : 0));
    }

    /**
     * @param {number} x
     * @param {number} y
     * @returns {number} the value of that tile, or -1 if invalid
     */
    getCoord(x, y) {
        if (x < 0 || y < 0 || x >= this.map[0].length || y >= this.map.length) {
            return -1;
        }
        return this.map[y][x];
    }

    /**
     * @param {number} x
     * @param {number} y
     * @returns {number} the number of adjacent tiles that are >= 1
     */
    countAdjacent(x, y) {
        return [
            // top-left
            this.getCoord(x - 1, y - 1) >= 1,
            // top
            this.getCoord(x, y - 1) >= 1,
            // top-right
            this.getCoord(x + 1, y - 1) >= 1,
            // right
            this.getCoord(x + 1, y) >= 1,
            // bottom-right
            this.getCoord(x + 1, y + 1) >= 1,
            // bottom
            this.getCoord(x, y + 1) >= 1,
            // bottom-left
            this.getCoord(x - 1, y + 1) >= 1,
            // left
            this.getCoord(x - 1, y) >= 1
        ].reduce((acc, v) => !!v ? acc + 1 : acc, 0);
    }

    /**
     * transform in place the map replacing any rolls (1) with (2) if they are accessible
     * @returns {PrintingDepartmentMap}
     */
    markAccessable() {
        for (let y = 0; y < this.map.length; y += 1) {
            for (let x = 0; x < this.map[0].length; x += 1) {
                if (this.map[y][x] < 1) continue;
                if (this.countAdjacent(x, y) < 4) {
                    this.map[y][x] = 2;
                }

            }
        }
        return this;
    }

    /** @returns {number} the number of removed rolls */
    removeAccessable() {
        let removed = 0;
        for (let y = 0; y < this.map.length; y += 1) {
            for (let x = 0; x < this.map[0].length; x += 1) {
                if (this.map[y][x] === 2) {
                    removed += 1;
                    this.map[y][x] = 0;
                }
            }
        }
        return removed;
    }
}

const map = new PrintingDepartmentMap(input);

let removed = 0;
while (true) {
    const justRemoved = map.markAccessable().removeAccessable();
    if (removed === 0) {
        console.log(`Part 1 Answer: ${justRemoved}`);
    }
    if (justRemoved === 0) break;
    removed += justRemoved;
}

console.log(`Part 2 Answer: ${removed}`);

You can replace the require(‘fs’) on the first line with the input and run it in your browser console as well.

const input = require('fs').readFileSync('input-day2.txt', 'utf-8');

let idsPart1 = [];
let idsPart2 = [];

input.split(',').forEach(range => {
    const [start, end] = range.split('-').map(v => parseInt(v, 10));
    let cursor = start;

    while (cursor <= end) {
        const cursorString = cursor.toString(10);

        // part 1 check
        let halfLength = Math.floor(cursorString.length / 2);
        let left = cursorString.slice(0, halfLength);
        let right = cursorString.slice(halfLength, cursorString.length);
        if (left === right) {
            idsPart1.push(cursor);
        }

        // part 2 check
        let sequenceLength = 1;
        while (sequenceLength <= halfLength) {
            const sequence = cursorString.slice(0, sequenceLength);
            let builtString = sequence;
            while (builtString.length < cursorString.length) {
                builtString = `${builtString}${sequence}`;
            }
            if (builtString === cursorString) {
                idsPart2.push(cursor);
                break;
            }

            sequenceLength += 1;
        }

        cursor += 1;
    }
})

const answer1 = idsPart1.flat().reduce((acc, cur) => acc += cur, 0);
const answer2 = idsPart2.flat().reduce((acc, cur) => acc += cur, 0);

console.log(`Part 1 Answer: ${answer1}`);
console.log(`Part 2 Answer: ${answer2}`);

let position = 50;
let answer1 = 0;
let answer2 = 0;

const sequence = require('fs').readFileSync('input-day1.txt', 'utf-8');

sequence.split('\n').forEach(instruction => {
    const turn = instruction.charAt(0);
    let distance = parseInt(instruction.slice(1), 10);

    while (distance > 0) {
        distance -= 1;

        if (turn === 'L') {
            position -= 1;
        } else if (turn === 'R') {
            position += 1;
        }

        if (position >= 100) {
            position -= 100;
        } else if (position < 0) {
            position += 100;
        }

        if (position === 0) {
            answer2 += 1;
        }
    }

    if (position === 0) {
        answer1 += 1;
    }
});

console.log(`Part 1 Answer: ${answer1}`);
console.log(`Part 2 Answer: ${answer2}`);