66 lines
2.6 KiB
Nim
66 lines
2.6 KiB
Nim
import ./common, std/[strutils, sequtils, strformat, sugar, sets, math]
|
|
|
|
proc parseLine(s: string): seq[seq[string]] = s.split(" | ").mapIt(it.split(" "))
|
|
|
|
proc p1(c: seq[string]): int =
|
|
c.reduce((a: int, l) =>
|
|
a + l.parseLine()[1].reduce((b: int, h) => b + int(h.len() in [2, 3, 4, 7]), 0), 0)
|
|
|
|
proc numShared(s1: string, s2: string): int = (s1.toHashSet() * s2.toHashSet()).len()
|
|
proc p2(c: seq[string]): int =
|
|
for oLine in c.map(parseLine):
|
|
let four = oLine[0].findFirst((s) => s.len() == 4)
|
|
let seven = oLine[0].findFirst((s) => s.len() == 3)
|
|
for i, output in oLine[1].pairs():
|
|
let outputVal = case output.len():
|
|
of 2: 1
|
|
of 3: 7
|
|
of 4: 4
|
|
of 7: 8
|
|
of 5:
|
|
case output.numShared(four) + output.numShared(seven):
|
|
of 4: 2
|
|
of 6: 3
|
|
else: 5
|
|
else:
|
|
case output.numShared(four) + output.numShared(seven):
|
|
of 6: 0
|
|
of 5: 6
|
|
else: 9
|
|
result += outputVal * int(10 ^ (abs(oLine[1].len() - i) - 1))
|
|
|
|
# Explanation:
|
|
# 1, 7, 8, and 4 are known and may be identified just by length, so we only
|
|
# need to figure out the 5- and 6- inputs, 0, 2, 3, 5, 6, and 9
|
|
# we should be able to do this by seeing how many segments are shared with the
|
|
# known digits
|
|
# 5-inputs: 235
|
|
# 2: shares 2 with 4, 1 with 1, 2 with 7
|
|
# 3: shares 3 with 4, 2 with 1, 3 with 7
|
|
# 5: shares 3 with 4, 1 with 1, 2 with 7
|
|
# 6-inputs: 069
|
|
# 0: shares 3 with 4, 2 with 1, 3 with 7
|
|
# 6: shares 3 with 4, 1 with 1, 2 with 7
|
|
# 9: shares 4 with 4, 2 with 1, 3 with 7
|
|
# from this information, we can identify each digit simply by knowing the
|
|
# number of shared segments with 4 and 7 alone:
|
|
# 2: 22
|
|
# 3: 33
|
|
# 5: 32
|
|
# 0: 33
|
|
# 6: 32
|
|
# 9: 43
|
|
|
|
doDay(8, (n) => n.loadInput(),
|
|
p1,
|
|
p2,
|
|
"""be cfbegad cbdgef fgaecd cgeb fdcge agebfd fecdb fabcd edb | fdgacbe cefdb cefbgd gcbe
|
|
edbfga begcd cbg gc gcadebf fbgde acbgfd abcde gfcbed gfec | fcgedb cgb dgebacf gc
|
|
fgaebd cg bdaec gdafb agbcfd gdcbef bgcad gfac gcb cdgabef | cg cg fdcagb cbg
|
|
fbegcd cbd adcefb dageb afcb bc aefdc ecdab fgdeca fcdbega | efabcd cedba gadfec cb
|
|
aecbfdg fbg gf bafeg dbefa fcge gcbea fcaegb dgceab fcbdga | gecf egdcabf bgf bfgea
|
|
fgeab ca afcebg bdacfeg cfaedg gcfdb baec bfadeg bafgc acf | gebdcfa ecba ca fadegcb
|
|
dbcfg fgd bdegcaf fgec aegbdf ecdfab fbedc dacgb gdcebf gf | cefg dcbef fcge gbcadfe
|
|
bdfegc cbegaf gecbf dfcage bdacg ed bedf ced adcbefg gebcd | ed bcgafe cdgba cbgef
|
|
egadfb cdbfeg cegd fecab cgb gbdefca cg fgcdab egfdb bfceg | gbdfcae bgc cg cgb
|
|
gcafb gcf dcaebfg ecagb gf abcdeg gaef cafbge fdbac fegbdc | fgae cfgab fg bagce""".split('\n'), 26, 61229)
|