Commit 0e35517

@@ -0,0 +1,59 @@
+<<-DOC
+A top secret message containing uppercase letters from 'A' to 'Z' has been encoded as numbers using the following mapping:
+
+'A' -> 1
+'B' -> 2
+...
+'Z' -> 26
+You are an FBI agent and you need to determine the total number of ways that the message can be decoded.
+
+Since the answer could be very large, take it modulo 109 + 7.
+
+Example
+
+For message = "123", the output should be
+
+mapDecoding(message) = 3.
+
+"123" can be decoded as "ABC" (1 2 3), "LC" (12 3) or "AW" (1 23), so the total number of ways is 3.
+
+Input/Output
+
+[time limit] 4000ms (rb)
+[input] string message
+
+A string containing only digits.
+
+Guaranteed constraints:
+
+0 ≤ message.length ≤ 105.
+
+[output] integer
+
+The total number of ways to decode the given message.
+DOC
+
+describe "map_decoding" do
+  def map_decoding(message)
+    0
+  end
+
+  [
+    { message: "123", expected: 3 },
+    { message: "12", expected: 2 },
+    { message: "0", expected: 0 },
+    { message: "1", expected: 1 },
+    { message: "11", expected: 2 },
+    { message: "301", expected: 0 },
+    { message: "1001", expected: 0 },
+    { message: "10122110", expected: 5 },
+    { message: "", expected: 1 },
+    { message: "11115112112", expected: 104 },
+    { message: "2871221111122261", expected: 233 },
+    { message: "1221112111122221211221221212212212111221222212122221222112122212121212221212122221211112212212211211", expected: 782204094 },
+  ].each do |x|
+    it do
+      expect(map_decoding(x[:message])).to eql(x[:expected])
+    end
+  end
+end