Advent of Code 2018: Day 9
Part 1 What is the winning Elf's score?
Example if placing a marble that's not a multiple of 23: unshift 1: [1, 0, (2)] --> [0, 2, 1] push: [0, 2, 1] --> [0, 2, 1, (3)]Example otherwise: shift 7: [11, 1, 12, 6, 13, 3, 14, 7, 15, 0, 16, 8, 17, 4, 18, 9, 19, 2, 20, 10, 21, 5, (22)] --> [19, 2, 20, 10, 21, 5, {22}, 11, 1, 12, 6, 13, 3, 14, 7, 15, 0, 16, 8, 17, 4, 18, 9] pop: [19, 2, 20, 10, 21, 5, 22, 11, 1, 12, 6, 13, 3, 14, 7, 15, 0, 16, 8, 17, 4, 18, 9] --> [19, 2, 20, 10, 21, 5, 22, 11, 1, 12, 6, 13, 3, 14, 7, 15, 0, 16, 8, 17, 4, 18] unshift 1: [19, 2, 20, 10, 21, 5, 22, 11, 1, 12, 6, 13, 3, 14, 7, 15, 0, 16, 8, 17, 4, 18] --> [2, 20, 10, 21, 5, 22, 11, 1, 12, 6, 13, 3, 14, 7, 15, 0, 16, 8, 17, 4, 18, (19)]
Deque.prototype.rotate = function rotate (n) { if (n >= 0) { for (let i = 0; i < n; i++) { this.push(this.shift()); } } else { for (let i = 0; i > n; i--) { this.unshift(this.pop()); } } }
function solve (marbles, players) { let scores = {}; let circle = new Deque([0]); for (let m = 1; m <= marbles; m++) { if (m % 23) { circle.rotate(1); circle.push(m); } else { circle.rotate(-7); scores[m % players] = (scores[m % players] || 0) + m + circle.pop(); circle.rotate(1); } } return Object.entries(scores).reduce( (max, next) => max > next[1] ? max : next[1], 0); }
numPlayers = Number(input.split(" ")[0])
numMarbles = Number(input.split(" ")[6])
part1Score = solve(numMarbles, numPlayers)
Part 2 What would the new winning Elf's score be if the number of the last marble were 100 times larger?
part2Score = solve(numMarbles * 100, numPlayers)
input = `403 players; last marble is worth 71920 points`
Deque = require('denque@1.4.0/index.js').catch(() => window.Denque)