Commit 93b5609

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day 13

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Lines changed: 1 addition & 1 deletion

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`@@ -14,7 +14,7 @@`
`14`	`14`	`\|[10](https://adventofcode.com/2020/day/10)\|Adapter Array\|[py](/day10/main.py), [alt](/day10/alt.py)\|`
`15`	`15`	`\|[11](https://adventofcode.com/2020/day/11)\|Seating System\|[py](/day11/main.py)\|`
`16`	`16`	`\|[12](https://adventofcode.com/2020/day/12)\|Rain Risk\|[py](/day12/main.py)\|`
`17`		`-\|[13](https://adventofcode.com/2020/day/13)\|-\|-\|`
	`17`	`+\|[13](https://adventofcode.com/2020/day/13)\|Shuttle Search\|[py](/day13/main.py)\|`
`18`	`18`	`\|[14](https://adventofcode.com/2020/day/14)\|-\|-\|`
`19`	`19`	`\|[15](https://adventofcode.com/2020/day/15)\|-\|-\|`
`20`	`20`	`\|[16](https://adventofcode.com/2020/day/16)\|-\|-\|`

Lines changed: 20 additions & 0 deletions

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`@@ -0,0 +1,20 @@`
	`1`	`+import numpy as np`
	`2`	`+from math import prod`
	`3`	`+`
	`4`	`+with open("input.txt") as f:`
	`5`	`+ lines = [x.strip() for x in f]`
	`6`	`+`
	`7`	`+arrival = int(lines[0])`
	`8`	`+buses = [(i, int(e)) for i, e in enumerate(lines[1].split(",")) if e.isdigit()]`
	`9`	`+`
	`10`	`+offsets, times = zip(*buses)`
	`11`	`+b = [e - (arrival % e) for e in times]`
	`12`	`+print(np.min(b) * times[np.argmin(b)])`
	`13`	`+`
	`14`	`+def chinese_remainder(ns, rems):`
	`15`	`+ p = prod(ns)`
	`16`	`+ x = sum(r * (p // n) * pow(p // n, -1, n) for r, n in zip(rems, ns))`
	`17`	`+ return x % p`
	`18`	`+`
	`19`	`+rems = [time-offset for offset, time in buses]`
	`20`	`+print(chinese_remainder(times, rems))`

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