Data commit

Task/Roman-numerals-Decode/Picat/roman-numerals-decode.picat

@@ -0,0 +1,44 @@
+go =>
+   List = ["IV",
+           "XLII",
+           "M",
+           "MCXI",
+           "CMXI",
+           "MCM",
+           "MCMXC",
+           "MMVIII",
+           "MMIX",
+           "MCDXLIV",
+           "MDCLXVI",
+           "MMXII"],
+   foreach(R in List)
+      printf("%-8s: %w\n", R, roman_decode(R))
+   end,
+   nl.
+
+
+roman_decode(Str) = Res =>
+  if Str == "" then
+    Res := ""
+  else
+    D = new_map(findall((R=D), roman(R,D))),
+    Res = 0,
+    Old = 0,
+    foreach(S in Str)
+      N = D.get(S),
+      % Fix for the Roman convention that XC = 90, not 110.
+      if Old > 0, N > Old then
+        Res := Res - 2*Old
+      end,
+      Res := Res + N,
+      Old := N
+    end
+  end.
+
+roman('I', 1).
+roman('V', 5).
+roman('X', 10).
+roman('L', 50).
+roman('C', 100).
+roman('D', 500).
+roman('M', 1000).