Day 4

day_04/solve.nim

@@ -0,0 +1,43 @@
+import std/[strutils, sequtils, sugar]
+
+type Assignment = object
+  first: int
+  last: int
+
+proc assignment(sections: string): Assignment {.inline.} =
+  let edges = sections.split("-")
+  return Assignment(first: edges[0].parseInt, last: edges[1].parseInt)
+
+proc contains(self: Assignment, other: Assignment): bool {.inline.} =
+  other.first >= self.first and other.last <= self.last
+
+proc intersects(self: Assignment, other: Assignment): bool {.inline.} =
+  other.last >= self.first and other.first <= self.last
+
+const input = readFile("day_04/input.txt")
+
+iterator elfPairs(data: string): tuple[elf1: Assignment, elf2: Assignment] =
+  for pair in input.splitLines:
+    let assignments = pair.split(",")
+    yield (
+      elf1: assignment(assignments[0]), 
+      elf2: assignment(assignments[1])
+    )
+
+proc solvePart1() =
+  var count = 0
+  for pair in input.elfPairs:
+    if pair.elf1.contains(pair.elf2) or pair.elf2.contains(pair.elf1):
+      count += 1
+  echo "Fully incuded pairs: " & $count
+
+proc solvePart2() =
+  var count = 0
+  for pair in input.elfPairs:
+    if pair.elf1.intersects(pair.elf2):
+      count += 1
+  echo "Intersecting pairs: " & $count
+
+if isMainModule:
+  solvePart1()
+  solvePart2()