13-->>python3

The Roman numerals contain the following seven characters:,,,, I V X L C , D and M .

Character          value I             1V             5X             10L             50C             100D             500M             1000

For example, the Roman numeral 2 is written II , that is, two parallel 1. 12 Write XII , that is X + II . 27 Write XXVII , that is XX + V + II .

Usually, the number of Roman numerals is small and the numbers are on the right side of the large numbers. But there are exceptions, such as 4 not IIII to write, but IV . The number 1 is on the left side of the number 5, the number represented is equal to the large number 5 decreases the number 1 gets the value 4. Similarly, the number 9 is represented as IX . This special rule applies only to the following six cases:

• ICan be placed on V X the left side of (5) and (10) to represent 4 and 9.
• XCan be placed on L C the left side of (50) and (100) to represent 40 and 90.
• CCan be placed on D M the left side of (500) and (1000) to represent 400 and 900.

Given a Roman number, convert it to an integer. The input is guaranteed to be within the range of 1 to 3999.

Example 1:

Input: "III" output: 3

Example 2:

Input: "IV" output: 4

Example 3:

Input: "IX" output: 9

Example 4:

Input: "LVIII" output: 58 Explanation: C = +, L = +, XXX = +, III = 3.

Example 5:

Input: "MCMXCIV" output: 1994 Explanation: M = +, CM = =, XC = all, IV = 4.

Analysis: required to convert Roman numerals to decimal numbers, first we need to know the mechanism of conversion. 　　If the input is a letter (Roman number), then the direct return of the letter represents the decimal number if it is two or more: starting from the first (i) to find out the judgment, if I represents the decimal number is greater than the i+1 represents, the sum, conversely, minus I represents the decimal number.　　This problem clearly requires the decimal number corresponding to the Roman numerals to be marked, and in Python, the dictionary operation can be easily solved. Use a dictionary to mark, and then parse and convert a given Roman number.

1 classSolution:2     defRomantoint (self, s):3         """4 : Type S:str5 : Rtype:int6         """7tag={'M': 1000,'D': 500,'C': 100,'L': 50,'X': 10,'V'75A'I': 1}8sum=09         ifLen (s) ==1:Ten             returnTag[s[-1]] One          forIinchRange (len (s)-1): A             ifTag[s[i]]<tag[s[i+1] ]: #tag [s[i]] denotes the key value of the letter -sum-=Tag[s[i]] -             Else: thesum+=Tag[s[i]] -              -         returnSUM+TAG[S[-1]]

13-->>python3