19 lines
1,000 B
JavaScript
19 lines
1,000 B
JavaScript
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// this was a tough one. I still don't fully understand what the puzzle was asking for. but i played around in excel and found this method to find the solution.
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const fs = require('fs');
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const input = fs.readFileSync('input.txt', 'utf-8').split('\n');
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const busses = input[1].split(',').map(n => Number(n)).map((v,i)=>[v,i]).filter(v => !isNaN(v[0]));
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console.log(busses)
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// start with a timestamp of 0
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let time = 0;
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// if you incrment by the ID of the first bus, the first bus will always meet the pattern described in the puzzle.
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let inc = busses[0][0]
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for (let bus = 1; bus < busses.length; bus++){
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// continue incrementing until the next bus meets the pattern described in the puzzle
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while (((time+busses[bus][1]) % busses[bus][0]) != 0) {
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time += inc
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}
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// now you can increment by the new bus that met the pattern, and it will continue to meet the pattern
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inc*=busses[bus][0]
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}
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// since we looped through all the busses, we know that all busses meet the pattern.
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console.log(time)
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