roman_numerals: iteration 1

cpp/roman-numerals/roman_numerals.cpp

@@ -1,7 +1,5 @@
 #include "roman_numerals.h"
 
-#include <string>
-#include <vector>
 
 namespace roman {
 
@@ -11,48 +9,35 @@ string convert(int number)
 {
     struct digit_t
     {
-        int    key;
-        string value;
+        int    value;
+        string presentation;
     };
 
-    static const vector<digit_t> digits = {
+    static const digit_t digits[] = {
         {1000, "M" },
+        {900,  "CM"},
         {500,  "D" },
+        {400,  "CD"},
         {100,  "C" },
+        {90,   "XC"},
         {50,   "L" },
+        {40,   "XL"},
         {10,   "X" },
+        {9,    "IX"},
         {5,    "V" },
+        {4,    "IV"},
         {1,    "I" }
     };
 
     string result;
 
-    auto append_digit = [&](int key, const string &value) -> void {
+    for (auto &digit : digits) {
 
-                            while (number >= key) {
+        while (number >= digit.value) {
 
-                                result += value;
-                                number -= key;
-                            }
-                        };
-
-    auto iter = digits.cbegin();
-    for (; iter != digits.cend(); ++iter) {
-
-        append_digit(iter->key, iter->value);
-
-        auto next_iter = next(iter);
-
-        while (next_iter != digits.cend()
-                && 2*next_iter->key >= iter->key) {
-            ++next_iter;
+            result += digit.presentation;
+            number -= digit.value;
         }
-
-        if (next_iter == digits.cend())
-            continue;
-
-        append_digit(iter->key - next_iter->key,
-                     next_iter->value + iter->value);
     }
 
     return result;