56 lines
1.2 KiB
JavaScript
56 lines
1.2 KiB
JavaScript
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const input = (await Bun.file("input.txt").text()).trim()
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// const input = "12345";
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const files = [];
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const spaces = [];
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let pos = 0;
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for (let i = 0; i < input.length; i++ ) {
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const size = parseInt(input[i])
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if (i % 2 == 0) {
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files.push({size, id: i / 2, start: pos,})
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} else {
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spaces.push({size, start: pos})
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}
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pos += size;
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}
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const inserted = [];
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let j = 0;
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let end;
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for (let i = files.length - 1; j < spaces.length; i--) {
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const file = files[i];
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let rem = file.size;
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while (rem > 0) {
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const space = spaces[j];
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if (space.start > file.start) {
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end = file.start + file.size;
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break;
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};
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const amt = Math.min(space.size, files[i].size)
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spaces[j] = {size: space.size - amt, start: space.start + amt};
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inserted.push({id: file.id, start: space.start, size: amt,})
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files[i] = {id: file.id, start: file.start, size: files[i].size - amt,};
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rem -= amt;
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if (amt == space.size) j++
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}
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if (end) break
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}
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const newfiles = files.concat(inserted)
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.filter(file => file.size > 0)
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.sort((a, b) => a.start > b.start)
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const checksum = newfiles.reduce((acc, current) => acc + (current.id * current.size * (current.start + (current.size - 1) / 2)), 0)
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console.log(checksum)
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