The avatar for @jwolondon
Jo Wood
Professor of Visual Analytics interested in design, geovisualization, visual storytelling and computational thinking.
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Ξ🎄Advent of Code 2024
Edited
Dec 7
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Ξ🎄Advent of Code 2024
Advent of Code: 2024 Day 1Advent of Code: 2024 Day 2Advent of Code: 2024 Day 3Advent of Code: 2024 Day 4Advent of Code: 2024 Day 5Advent of Code: 2024 Day 6
Advent of Code: 2024 Day 7
Advent of Code: 2024 Day 8Advent of Code: 2024 Day 9Advent of Code: 2024 Day 10Advent of Code: 2024 Day 11Advent of Code: 2024 Day 12Advent of Code: 2024 Day 13Advent of Code: 2024 Day 14Advent of Code: 2024 Day 18Advent of Code: 2024 Day 19Advent of Code: 2024 Day 21Advent of Code: 2024 Day 22Advent of Code: 2024 Day 23Advent of Code: 2024 Day 25
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function parse(input) {
return input.split("\n").map((d) => {
const nums = d.split(" ");
return {
result: Number(nums[0].slice(0, -1)),
operands: nums.slice(1).reverse().map(Number)
};
});
}
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function validExpr(total, operands) {
if (operands.length === 1) {
return operands[0] === total;
}

const [canDiv, canSub] = [total % operands[0] === 0, total >= operands[0]];

if (!canDiv && !canSub) {
return false;
}

return (
(canDiv && validExpr(total / operands[0], operands.slice(1))) ||
(canSub && validExpr(total - operands[0], operands.slice(1)))
);
}
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function part1(input) {
return d3.sum(
parse(input).filter((d) => validExpr(d.result, d.operands)),
(d) => d.result
);
}
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function validExpr2(total, operands) {
if (operands.length === 1) {
return operands[0] === total;
}

const canDiv = total % operands[0] === 0;
const canSub = total >= operands[0];
const canCat = String(total).endsWith(operands[0]);

if (!canDiv && !canSub && !canCat) {
return false;
}

return (
(canDiv && validExpr2(total / operands[0], operands.slice(1))) ||
(canSub && validExpr2(total - operands[0], operands.slice(1))) ||
(canCat &&
validExpr2(
Number(String(total).slice(0, -String(operands[0]).length)),
operands.slice(1)
))
);
}
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function part2(input) {
return d3.sum(
parse(input).filter((d) => validExpr2(d.result, d.operands)),
(d) => d.result
);
}
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