50 lines
1.1 KiB
TypeScript
50 lines
1.1 KiB
TypeScript
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const inputFile = await Bun.file("input").text();
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const lines = inputFile.split("\n").filter((x) => x);
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function between(x: number, min: number, max: number): boolean {
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return x >= min && x < max;
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}
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function countMs(str: string) {
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return (str.match(/M/g) || []).length;
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}
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function countSs(str: string) {
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return (str.match(/S/g) || []).length;
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}
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let xmasCount = 0;
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for (let lineIdx = 0; lineIdx < lines.length; lineIdx++) {
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for (let charIdx of lines[lineIdx]
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.matchAll(/A/g)
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.toArray()
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.map((m) => m.index)) {
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let charPositions = [
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[lineIdx - 1, charIdx - 1], // up left
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[lineIdx - 1, charIdx + 1], // up right
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[lineIdx + 1, charIdx - 1], // down left
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[lineIdx + 1, charIdx + 1], // down right
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].filter(
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([li, ci]) =>
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between(li, 0, lines.length) && between(ci, 0, lines[lineIdx].length),
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);
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if (charPositions.length === 4) {
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let corners = "";
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for (let [li, ci] of charPositions) {
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corners += lines[li][ci];
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}
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if (countMs(corners) == 2 && countSs(corners) == 2) {
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xmasCount += 1;
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}
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}
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}
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}
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console.log(xmasCount);
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export {};
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