1 files changed, 39 insertions, 0 deletions

diff --git a/day06/solution.nim b/day06/solution.nim
new file mode 100644
index 0000000..ce3ccd0
--- /dev/null
+++ b/day06/solution.nim
@@ -0,0 +1,39 @@
+import std/strutils
+import std/sequtils
+import std/tables
+
+proc solve(message: string, nUniq: int): int =
+  var cntUniq = initCountTable[char]()
+
+  # init found
+  var uniq = 0
+  for c in message[0 ..< nUniq]:
+    cntUniq.inc(c)
+    if cntUniq[c] == 1:
+      uniq += 1
+
+  let pairs = zip(
+    message[0 ..< message.len()-nUniq],
+    message[nUniq ..< message.len()])
+
+  for i, pair in pairs:
+    if uniq == nUniq:
+      return i+nUniq
+
+    cntUniq.inc(pair[0], -1)
+    if cntUniq[pair[0]] == 0:
+      # we lost one uniq number in sequence
+      uniq -= 1
+
+    cntUniq.inc(pair[1])
+    if cntUniq[pair[1]] == 1:
+      # we found new uniq number in sequence
+      uniq += 1
+
+  assert(false)
+  return -1
+
+let content = readFile("./input.txt").strip()
+
+echo solve(content, 4)
+echo solve(content, 14)