weeks 14-26, 258 in Nim

3 files changed, 98 insertions, 0 deletions

diff --git a/challenge-015/archargelod/README b/challenge-015/archargelod/README
new file mode 100644
index 0000000000..6cd57e1074
--- /dev/null
+++ b/challenge-015/archargelod/README
@@ -0,0 +1 @@
+Solution by archargelod
diff --git a/challenge-015/archargelod/nim/ch_1.nim b/challenge-015/archargelod/nim/ch_1.nim
new file mode 100755
index 0000000000..dd645f1540
--- /dev/null
+++ b/challenge-015/archargelod/nim/ch_1.nim
@@ -0,0 +1,48 @@
+#!/usr/bin/env -S nim r -d:release --verbosity:0 --hints:off
+import std/math
+
+proc primeSieve(max: int): seq[int] =
+  var sieve = newSeq[bool](max)
+
+  for p in 2 .. sieve.high:
+    if sieve[p]:
+      continue
+
+    for i in countUp(2 * p, sieve.high, p):
+      sieve[i] = true
+
+  for i, notPrime in sieve[2 ..^ 1]:
+    if not notPrime:
+      result.add i + 2
+
+proc tierPrimesByStrength(
+    primes: openArray[int]
+): tuple[weak, balanced, strong: seq[int]] =
+  for pInd, prime in primes[0 ..^ 2]:
+    if pInd == 0:
+      continue
+    let mean = (primes[pInd - 1] + primes[pInd + 1]) / 2
+
+    if almostEqual(prime.float, mean):
+      result.balanced.add prime
+    elif prime.float > mean:
+      result.strong.add prime
+    elif prime.float < mean:
+      result.weak.add prime
+    else:
+      raiseAssert("Error: bad float comparison.")
+
+when isMainModule:
+  import std/unittest
+
+  const
+    ExpectedWeak = [3, 7, 13, 19, 23, 31, 43, 47, 61, 73]
+    ExpectedStrong = [11, 17, 29, 37, 41, 59, 67, 71, 79, 97]
+
+  suite "Strong and weak primes":
+    let (weak, _, strong) = tierPrimesByStrength(primeSieve(200))
+
+    test "first 10 weak primes":
+      check weak[0 ..< 10] == ExpectedWeak
+    test "first 10 strong primes":
+      check strong[0 ..< 10] == ExpectedStrong
diff --git a/challenge-015/archargelod/nim/ch_2.nim b/challenge-015/archargelod/nim/ch_2.nim
new file mode 100755
index 0000000000..18770f6d15
--- /dev/null
+++ b/challenge-015/archargelod/nim/ch_2.nim
@@ -0,0 +1,49 @@
+#!/usr/bin/env -S nim r -d:release --verbosity:0 --hints:off
+import std/[strutils, math]
+
+type cipherMode = enum
+  Encode
+  Decode
+
+proc alphaOrd(c: char): int =
+  c.ord - 'a'.ord
+
+proc rot(c: sink char, shift: int): char =
+  char('a'.ord + euclMod(c.alphaOrd + shift, 26))
+
+proc vigenereCipher(plaintext: var string, key: string, mode = Encode) =
+  for i, c in plaintext:
+    if c notin Letters:
+      continue
+
+    let key = block:
+      let tmp = key[i mod key.len].toLowerAscii.alphaOrd
+      if mode == Decode: -tmp else: tmp
+
+    plaintext[i] = c.toLowerAscii.rot(key)
+
+proc encode*(plaintext: var string, key: string) =
+  vigenereCipher(plaintext, key, Encode)
+
+proc decode*(plaintext: var string, key: string) =
+  vigenereCipher(plaintext, key, Decode)
+
+
+when isMainModule:
+  import std/unittest
+
+  const
+    Plaintext = "attacking tonight"
+    Key = "OCULORHINOLARINGOLOGY"
+    ExpectedEncoded = "ovnlqbpvt eoeqtnh"
+
+  suite "Vigenère cipher":
+    var text = Plaintext
+
+    test "encode sample text":
+      text.encode(Key)
+      check text == ExpectedEncoded
+
+    test "decode sample text":
+      text.decode(Key)
+      check text == Plaintext