day9-part2.js

inputString.split('\n').flatMap((e, i) => i === 0 ? [e, e] : e).map(e => [e.split(' ')[0], parseInt(e.split(' ')[1])]).map((e, i, arr) => i === 0 ? window.obj = { knots: Array(10).fill().map(_ => { return { x: 0, y: 0 } }), visited: Array(10).fill().map(_ => new Set()), increment: function (isX, n) { Array(10).fill(0).map((_, knotIndex) => knotIndex === 0 ? ( isX ? this.knots[knotIndex].x+=n : this.knots[knotIndex].y+=n ) : Array(2).fill(0).forEach(_ => this.distTooFar(knotIndex) ? Array(3).fill(0).forEach((_, i) => i === 0 ? ( this.knots[knotIndex].x = this.knots[knotIndex].x + Math.min(Math.max(this.knots[knotIndex-1].x-this.knots[knotIndex].x, -1), 1) ) : i === 1 ? ( this.knots[knotIndex].y = this.knots[knotIndex].y + Math.min(Math.max(this.knots[knotIndex-1].y-this.knots[knotIndex].y, -1), 1) ) : ( this.visited[knotIndex].add(this.knots[knotIndex].x + '-' + this.knots[knotIndex].y) ) ) : '' ) ) }, distTooFar: function (knotIndex) { return Math.abs(this.knots[knotIndex-1].x - this.knots[knotIndex].x) > 1 || Math.abs(this.knots[knotIndex-1].y - this.knots[knotIndex].y) > 1 } } : Array(e[1]).fill(0).forEach(_ => e[0] === 'L' ? window.obj.increment(true, -1) : e[0] === 'R' ? window.obj.increment(true, 1) : e[0] === 'U' ? window.obj.increment(false, 1) : window.obj.increment(false, -1) ) ).reduce((a, b) => window.obj.visited[window.obj.visited.length-1].size + 1)