Day Ten, Part I

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diff --git a/2020/input/ten.txt b/2020/input/ten.txt
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diff --git a/2020/ten.nim b/2020/ten.nim
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+# Day Ten: Adapter Array
+import os, strutils, sequtils, algorithm, math
+
+let input: string = paramStr(1)
+var adapters: seq[int] = map(split(strip(readFile(input)), '\n'), parseInt)
+adapters.add(0)
+adapters = sorted(adapters)
+adapters.add(adapters[^1] + 3)
+
+var jolt, one, three: int = 0
+for adapter in adapters:
+  case adapter - jolt
+  of 1:
+    inc(one)
+  of 3:
+    inc(three)
+  else:
+    discard
+  jolt = adapter
+
+echo one * three