PROBLEM DESCRIPTION
Given a string in roman no format (s) your task is to convert it to an integer . Various symbols and their values are given below.
1
2
3
4
5
6
7
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
SOLUTION
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class Solution {
public int romanToDecimal(String str) {
int n = str.length();
// store Roman numerals and their corresponding integer values
Map<String, Integer> map = new HashMap<>();
map.put("I", 1);
map.put("V", 5);
map.put("X", 10);
map.put("L", 50);
map.put("C", 100);
map.put("D", 500);
map.put("M", 1000);
int total = 0;
for (int i = 0; i < n; i++) {
// If the current character is the last one in the string
if (i == n - 1) {
// add its corresponding value
String current = String.valueOf(str.charAt(i));
total += map.get(current);
// If the current character is not the last one
// Compare it with the value for next character
} else {
String current = String.valueOf(str.charAt(i));
String next = String.valueOf(str.charAt(i + 1));
// Check if the current numeral is less than the next numeral
// We need to subtract the current value from total
if (map.get(current) < map.get(next)) {
total -= map.get(current);
// Otherwise the value can be added
} else {
total += map.get(current);
}
}
}
return total;
}
}