re-solve "13. Roman to Integer"

.plan

@@ -1,6 +1,7 @@
 Sep 10, 2024
 
 * re-solve "42. Trapping Rain Water"
+* re-solve "13. Roman to Integer"
 
 Sep 9, 2024
 

src/roman_to_integer.py

@@ -1,4 +1,4 @@
-ROMAN: dict[str, int] = {
+ROMAN_TO_INT = {
     "I": 1,
     "V": 5,
     "X": 10,
@@ -10,20 +10,17 @@
 
 
 class Solution:
-    def romanToInt(self, roman: str) -> int:
-        assert roman
+    def romanToInt(self, s: str) -> int:
+        n = len(s)
+        prev = result = ROMAN_TO_INT[s[0]]
 
-        last_int_value = ROMAN[roman[0]]
-        result = 0
+        for i in range(1, n):
+            x = ROMAN_TO_INT[s[i]]
 
-        for letter in roman:
-            int_value = ROMAN[letter]
-
-            if int_value > last_int_value:
-                result += int_value - last_int_value * 2
+            if x > prev:
+                result += x - 2 * prev
             else:
-                result += int_value
-
-            last_int_value = int_value
+                result += x
+            prev = x
 
         return result

tests/test_roman_to_integer.py

@@ -10,6 +10,7 @@
         ("IV", 4),
         ("IX", 9),
         ("LVIII", 58),
+        ("MCMXCIV", 1994),
     ],
 )
 def test_solution(roman, integer):