56 lines
1.6 KiB
TypeScript
56 lines
1.6 KiB
TypeScript
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const fs = require('fs');
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const input = fs.readFileSync(__dirname + '/input.txt', 'utf8');
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const lines = input.split("\n");
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interface Coord { x: number, y: number };
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interface equation {
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prize: Coord,
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a: Coord,
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b: Coord,
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}
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const equations: Array<equation> = [];
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for (let i = 0; i < lines.length; i += 4) {
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let match = lines[i].match(/Button A: X\+(\d+), Y\+(\d+)/);
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const a = { x: parseInt(match[1]), y: parseInt(match[2]) };
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match = lines[i + 1].match(/Button B: X\+(\d+), Y\+(\d+)/);
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const b = { x: parseInt(match[1]), y: parseInt(match[2]) };
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match = lines[i + 2].match(/Prize: X=(\d+), Y=(\d+)/);
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const prize = { x: parseInt(match[1]), y: parseInt(match[2]) };
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// Part 2
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prize.x += 10000000000000;
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prize.y += 10000000000000;
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equations.push({ prize, a, b });
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}
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let result = 0;
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equations.forEach(({ a, b, prize }) => {
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// x*94 + y*22 = 8400
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// x*34 + y*67 = 5400
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// x = (8400 - y*22)/94
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// ((8400 - y*22)/94)*34 + y*67 = 5400
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// (8400 - y*22) + ((y*67*94)/34) = 5400 * 94/34
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// ((y*67*94)/34) - y*22 = ((5400 * 94/34)/34) - 8400
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// y * (((67*94)/34) - 22) = ((5400 * 94)/34) - 8400
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// y = (((5400 * 94)/34) - 8400) / (((67*94)/34) - 22)
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const bPresses = (((prize.y * a.x) / a.y) - prize.x) / (((b.y * a.x) / a.y) - b.x);
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const aPresses = (prize.x - (bPresses * b.x)) / a.x;
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if (
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Math.abs(bPresses - Math.round(bPresses)) < 0.001
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&& Math.abs(aPresses - Math.round(aPresses)) < 0.001
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&& aPresses > 0 && bPresses > 0
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) {
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result += (Math.round(aPresses) * 3) + Math.round(bPresses);
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}
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});
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console.log(result);
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