solve day 1

solutions/day01/example.txt

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+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet

solutions/day01/example2.txt

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+two1nine
+eightwothree
+abcone2threexyz
+xtwone3four
+4nineeightseven2
+zoneight234
+7pqrstsixteen

solutions/day01/solution.nim

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+import std/[strutils]
+
+const example* = slurp("example.txt").strip()
+const example2* = slurp("example2.txt").strip()
+const input* = slurp("input.txt").strip()
+
+proc parseInput(input: string): seq[string] =
+  input.split("\n")
+
+proc partOne*(input: string): int =
+  let lines = parseInput(input)
+  for line in lines:
+    var digits: seq[char]
+    for c in line:
+      case c
+      of '0'..'9':
+        digits.add c
+      else: discard
+    result += parseInt(digits[0] & digits[^1])
+
+type
+  Number = enum
+    zero = 0,
+    one, two, three, four, five, six, seven, eight, nine
+
+proc partTwo*(input: string): int =
+  let lines = parseInput(input)
+  for line in lines:
+    var digits: seq[char]
+    var i: int
+    while i < line.len:
+      let c = line[i]
+      case c
+      of '0'..'9':
+        digits.add c
+        inc i
+      else:
+        for number in Number.low..Number.high:
+          if line[i..^1].startsWith($number):
+            digits.add $number.ord
+            # some numbers share chars
+            # let's jump back an extra index to catch them
+            i += len($number)-2
+            break
+        inc i
+    result += parseInt(digits[0] & digits[^1])
+
+when isMainModule:
+  import std/unittest
+  suite "day 1":
+    test "part one":
+      check partOne(example) == 142
+      check partOne(input) == 54597
+    test "part two":
+      check partTwo(example2) == 281
+      check partTwo(input) == 54504