Data commit

Task/CUSIP/Swift/cusip.swift

@@ -0,0 +1,67 @@
+struct CUSIP {
+  var value: String
+
+  private static let alphabet = Array("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+  init?(value: String) {
+    if value.count == 9 && String(value.last!) == CUSIP.checkDigit(cusipString: String(value.dropLast())) {
+      self.value = value
+    } else if value.count == 8, let checkDigit = CUSIP.checkDigit(cusipString: value) {
+      self.value = value + checkDigit
+    } else {
+      return nil
+    }
+  }
+
+  static func checkDigit(cusipString: String) -> String? {
+    guard cusipString.count == 8, cusipString.allSatisfy({ $0.isASCII }) else {
+      return nil
+    }
+
+    let sum = cusipString.uppercased().enumerated().reduce(0, {sum, pair in
+      let (i, char) = pair
+      var v: Int
+
+      switch char {
+      case "*":
+        v = 36
+      case "@":
+        v = 37
+      case "#":
+        v = 38
+      case _ where char.isNumber:
+        v = char.wholeNumberValue!
+      case _:
+        v = Int(char.asciiValue! - 65) + 10
+      }
+
+      if i & 1 == 1 {
+        v *= 2
+      }
+
+      return sum + (v / 10) + (v % 10)
+    })
+
+    return String((10 - (sum % 10)) % 10)
+  }
+}
+
+let testCases = [
+  "037833100",
+  "17275R102",
+  "38259P508",
+  "594918104",
+  "68389X106",
+  "68389X105"
+]
+
+for potentialCUSIP in testCases {
+  print("\(potentialCUSIP) -> ", terminator: "")
+
+  switch CUSIP(value: potentialCUSIP) {
+  case nil:
+    print("Invalid")
+  case _:
+    print("Valid")
+  }
+}