Advent of Code: 2020 Day 15 / Jo Wood

Jo Wood

Professor of Visual Analytics interested in design, geovisualization, visual storytelling and computational thinking.

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Ξ🎄Advent of Code 2020

Edited

Nov 11, 2022

Fork of Advent of Code: 2020 Day 16

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function vanEck(history, spoken, n) {

const numInitialItems = history.reduce((x) => x + 1, 0);

for (let turn = numInitialItems; turn < n - 1; turn++) {

if (spoken in history) {

const last = history[spoken];

history[spoken] = turn;

spoken = turn - last;

} else {

history[spoken] = turn;

spoken = 0;

}

return spoken;

}

function initHistory(input) {

const initSequence = AOC.cloneArray(input);

const history = [];

const current = initSequence.pop();

initSequence.forEach((n, i) => (history[n] = i));

return [history, current];

}

function part1(input) {

return vanEck(...initHistory(input), 2020);

}

function part2(input) {

return vanEck(...initHistory(input), 30000000);

}

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