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Much better solution

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This commit is contained in:
Daniel Flanagan 2021-12-14 16:38:30 -06:00
parent 653b8d55dd
commit 3926ea400b
Signed by: lytedev
GPG key ID: 5B2020A0F9921EF4
1 changed files with 23 additions and 25 deletions
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48
2021/nim/day14.nim
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@ -6,31 +6,29 @@ proc parse(input: Lines): (string, Table[(char, char), char]) =
var c = input[i].split(" -> ")
result[1][(c[0][0], c[0][1])] = c[1][0]
proc stepPolymer(polymer: string, combis: Table[(char, char), char]): string =
result.add polymer[0]
var i = 1
while i < polymer.len:
var key = (polymer[i-1], polymer[i])
if combis.contains key: result.add combis[key]
result.add polymer[i]
i += 1
proc p1(input: Lines): uint64 =
proc steps(input: Lines, steps: uint): uint64 =
var (polymer, combis) = input.parse
for i in 1..10:
polymer = polymer.stepPolymer combis
var pps = polymer.toCountTable.values.toSeq
uint64(max(pps) - min(pps))
proc p2(input: Lines): uint64 =
var (polymer, combis) = input.parse
for i in 1..40:
echo &"Step {i}"
polymer = polymer.stepPolymer combis
var t = initTable[char, uint64]()
for c in polymer:
inc t[c]
var pps = t.values.toSeq
var pCounter = initTable[(char, char), uint64]()
var cCounter = initTable[char, uint64]()
for k in combis.keys:
pCounter[k] = 0
cCounter[k[0]] = 0
cCounter[k[1]] = 0
inc cCounter[polymer[0]]
for i in 1..<polymer.len:
inc pCounter[(polymer[i-1], polymer[i])]
inc cCounter[polymer[i]]
for i in 1..steps:
var newPCounter = pCounter
for t, n in pCounter.pairs:
let (l, r) = t
var twixt = combis[(l, r)]
newPCounter[(l, r)] -= n
newPCounter[(l, twixt)] += n
newPCounter[(twixt, r)] += n
cCounter[twixt] += n
pCounter = newPCounter
var pps = cCounter.values.toSeq
max(pps) - min(pps)
const input = """
@ -53,4 +51,4 @@ BC -> B
CC -> N
CN -> C
""".strip().split('\n').mapIt(it.strip)
doDayX 14, n => n.loadInput, p1, p2, (input, 1588'u64, 2188189693529'u64)
doDayX 14, n => n.loadInput, (i) => steps(i, 10), (i) => steps(i, 40), (input, 1588'u64, 2188189693529'u64)