13 - Roman to Integer
Written on October 21, 2015
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Given a roman numeral, convert it to an integer. The answer is guaranteed to be within the range from 1 to 3999.
public class Solution {
public int romanToInt(String s) {
if (s == null || s.length() == 0) return 0;
char[] roman = {'I','V','X','L','C','D','M'};
int result = 0;
for (int i = s.length() - 1; i >= 0; i--) {
char c = s.charAt(i);
if (c == 'I') {
if (i < s.length() - 1 && (s.charAt(i + 1) == 'V' || s.charAt(i + 1) == 'X')) {
result -= 1;
} else {
result += 1;
}
} else if (c == 'V') {
result += 5;
} else if (c == 'X') {
if (i < s.length() - 1 && (s.charAt(i + 1) == 'L' || s.charAt(i + 1) == 'C')) {
result -= 10;
} else {
result += 10;
}
} else if (c == 'L') {
result += 50;
} else if (c == 'C') {
if (i < s.length() - 1 && (s.charAt(i + 1) == 'D' || s.charAt(i + 1) == 'M')) {
result -= 100;
} else {
result += 100;
}
} else if (c == 'D') {
result += 500;
} else if (c == 'M') {
result += 1000;
}
}
return result;
}
}
class Solution(object):
def romanToInt(self, s):
"""
:type s: str
:rtype: int
"""
nums = []
for char in s:
if char == "M":
nums.append(1000)
elif char == "D":
nums.append(500)
elif char == "C":
nums.append(100)
elif char == "L":
nums.append(50)
elif char == "X":
nums.append(10)
elif char == "V":
nums.append(5)
elif char == "I":
nums.append(1)
ret = 0
for i, num in enumerate(nums[:-1]):
if num < nums[i + 1]:
ret -= num
else:
ret += num
return ret + nums[-1]
