Nim day 2

day02.nim

@@ -0,0 +1,40 @@
+import sequtils, strutils
+
+proc checksum(ids: seq[string]): int =
+    var pairCount, tripCount: int
+    for id in ids:
+        var pairs, trips: bool
+        for c in id:
+            var count = id.count(c)
+            if count == 2 and not pairs:
+                pairs = true
+                pairCount.inc
+            if count == 3 and not trips:
+                trips = true
+                tripCount.inc
+            if pairs and trips:
+                break
+    pairCount * tripCount
+
+proc difference(pairs: seq[tuple[a: char, b: char]]): string =
+    var difference: bool
+    for pair in pairs:
+        if pair.a != pair.b:
+            if difference:
+                return ""
+            else:
+                difference = true
+        else:
+            result &= pair.a
+
+proc max_common(ids: seq[string]): string =
+    for i, id1 in ids:
+        for id2 in ids[i+1 .. ids.high]:
+            let difference = zip(id1, id2).difference
+            if difference != "":
+                return difference
+    
+
+let ids = readFile("data/02.txt").strip.splitlines
+echo ids.checksum
+echo ids.max_common