Discussion on: Advent of Code 2019 Solution Megathread - Day 3: Crossed Wires

const closestIntersectionToOrigin = (wirePath1, wirePath2) => {
    const trace1 = traceWire(wirePath1);
    const trace2 = traceWire(wirePath2);

    // find intersection of traces
    const intersects = trace1.filter(x => trace2.includes(x));
    const distanceArr = intersects
        .slice(1)
        .map(x => manhattanDistance([0, 0], x.split(',').map(Number)));
    return Math.min(...distanceArr);
};

const leastStepsIntersection = (wirePath1, wirePath2) => {
    const trace1 = traceWire(wirePath1);
    const trace2 = traceWire(wirePath2);

    // find intersection of traces
    const intersects = trace1.filter(x => trace2.includes(x));
    const distanceArr = intersects.slice(1).map(x => {
        const totalSteps = trace2.findIndex(y => y == x) + trace1.findIndex(y => y == x);
        return totalSteps;
    });
    return Math.min(...distanceArr);
};

const traceWire = (wirePath, acc = ['0,0']) => {
    for (let i = 0; i < wirePath.length; i++) {
        const move = wirePath[i];
        const direction = move[0];
        const steps = Number(move.slice(1));

        const start = acc[acc.length - 1].split(',').map(Number);
        let [x, y] = start;

        const stepMap = {
            R: () => `${x},${++y}`,
            L: () => `${x},${--y}`,
            U: () => `${++x},${y}`,
            D: () => `${--x},${y}`
        };

        for (let j = 0; j < steps; j++) {
            acc.push(stepMap[direction]());
        }
    }
    return acc;
};

const manhattanDistance = (pos1, pos2) => Math.abs(pos2[0] - pos1[0]) + Math.abs(pos2[1] - pos1[1]);

if (!module.parent) {
    const wire1 = ['R75', 'D30', 'R83', 'U83', 'L12', 'D49', 'R71', 'U7', 'L72'];
    const wire2 = ['U62', 'R66', 'U55', 'R34', 'D71', 'R55', 'D58', 'R83'];

    console.log(leastStepsIntersection(wire1, wire2));
}
module.exports = { closestIntersectionToOrigin, leastStepsIntersection };