Problem

Roman numerals are represented by seven different symbols: `I`, `V`, `X`, `L`, `C`, `D` and `M`.

Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000

For example, two is written as `II` in Roman numeral, just two one’s added together. Twelve is written as, `XII`, which is simply `X` + `II`. The number twenty seven is written as `XXVII`, which is `XX` + `V` + `II`.

Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not `IIII`. Instead, the number four is written as `IV`. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as `IX`. There are six instances where subtraction is used:

• `I` can be placed before `V` (5) and `X` (10) to make 4 and 9.
• `X` can be placed before `L` (50) and `C` (100) to make 40 and 90.
• `C` can be placed before `D` (500) and `M` (1000) to make 400 and 900.

Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.

Example

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: L = 50, V= 5, III = 3.

Example 5:

Input: “MCMXCIV”
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.

Solution

``````impl Solution {
pub fn get_value(c: char) -> i32 {
match c {
'I' => return 1,
'V' => return 5,
'X' => return 10,
'L' => return 50,
'C' => return 100,
'D' => return 500,
'M' => return 1000,
_ => return 0,
}
}

pub fn roman_to_int(s: String) -> i32 {
let mut ret = 0;
let mut s1 = s.clone();

let mut temp = "".to_string();
let mut flag = false;

while s1.len() > 0 {
let c = s1.remove(0);

if temp.len() == 1 {
temp.push(c);

flag = false;
if temp == "CM" {
ret += 900;
} else if temp == "CD" {
ret += 400;
} else if temp == "XC" {
ret += 90;
} else if temp == "XL" {
ret += 40;
} else if temp == "IX" {
ret += 9;
} else if temp == "IV" {
ret += 4;
} else {
let cc = temp.remove(0);
ret += Solution::get_value(cc);

flag = true;
}

if flag == false {
temp.remove(0);
temp.remove(0);
}

} else if c == 'C' || c == 'X' || c == 'I' {
temp.push(c);
} else {
ret += Solution::get_value(c);
}
}

while temp.len() > 0 {
let cc = temp.remove(0);
ret += Solution::get_value(cc);
}
ret
}
}``````

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