#12. Integer to Roman

Author: papilo-cloud

Others/int_to_roman.py

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+# Seven different symbols represent Roman numerals with the following values:
+
+# Symbol	Value
+# I	1
+# V	5
+# X	10
+# L	50
+# C	100
+# D	500
+# M	1000
+# Roman numerals are formed by appending the conversions of decimal place values 
+# from highest to lowest. Converting a decimal place value into a Roman numeral 
+# has the following rules:
+
+# If the value does not start with 4 or 9, select the symbol of the maximal value
+# that can be subtracted from the input, append that symbol to the result, subtract
+# its value, and convert the remainder to a Roman numeral.
+# If the value starts with 4 or 9 use the subtractive form representing one symbol
+# subtracted from the following symbol, for example, 4 is 1 (I) less than 5 (V): IV
+# and 9 is 1 (I) less than 10 (X): IX. Only the following subtractive forms are 
+# used: 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD) and 900 (CM).
+# Only powers of 10 (I, X, C, M) can be appended consecutively at most 3 times
+# to represent multiples of 10. You cannot append 5 (V), 50 (L), or 500 (D) multiple
+# times. If you need to append a symbol 4 times use the subtractive form.
+# Given an integer, convert it to a Roman numeral.
+
+ 
+
+# Example 1:
+
+# Input: num = 3749
+
+# Output: "MMMDCCXLIX"
+
+# Explanation:
+
+# 3000 = MMM as 1000 (M) + 1000 (M) + 1000 (M)
+#  700 = DCC as 500 (D) + 100 (C) + 100 (C)
+#   40 = XL as 10 (X) less of 50 (L)
+#    9 = IX as 1 (I) less of 10 (X)
+# Note: 49 is not 1 (I) less of 50 (L) because the conversion is based on decimal places
+# Example 2:
+
+# Input: num = 58
+
+# Output: "LVIII"
+
+# Explanation:
+
+# 50 = L
+#  8 = VIII
+# Example 3:
+
+# Input: num = 1994
+
+# Output: "MCMXCIV"
+
+# Explanation:
+
+# 1000 = M
+#  900 = CM
+#   90 = XC
+#    4 = IV
+ 
+
+# Constraints:
+
+# 1 <= num <= 3999
+
+
+class Solution:
+    def intToRoman(self, num: int) -> str:
+        lists = [ ['M', 1000], ['CM', 900], ['D', 500], ['CD', 400], ['C', 100], 
+        ['XC', 90], ['L', 50], ['XL', 40], ['X', 10], ['IX', 9], ['V', 5], ['IV', 4], ['I',1]] 
+        ans = []
+            
+        for i in range(len(lists)):
+            a = lists[i][0]
+            b = lists[i][1]
+            while num >= b:
+                num -= b
+                ans.append(a)
+        return ''.join(ans)