12. Integer to Roman

Given an integer, convert it to a roman numeral.

Input is guaranteed to be within the range from 1 to 3999.

Solution 1

11ms 25.74%

public class Solution {
public String intToRoman(int num) {
String M[] = {"", "M", "MM", "MMM"};
String C[] = {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"};
String X[] = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"};
String I[] = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"};
return M[num/1000] + C[(num%1000)/100] + X[(num%100)/10] + I[num%10];
}
}

Solution 2

8ms 69.86%

public class Solution {
public String intToRoman(int num) {
int values[] = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
String[] strs = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" };
StringBuilder sb = new StringBuilder();
for (int i = 0; i < values.length; i++) {
while (num >= values[i]) {
num -= values[i];
sb.append(strs[i]);
}
}
return sb.toString();
}
}

Solution 3 11ms 25.74

public enum Type {
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);
private final int value;

Type(int value) {
this.value = value;
}
};

public String intToRoman3(int num) {
StringBuilder output = new StringBuilder();
for (Type t : Type.values()) {
while (num >= t.value) {
output.append(t);
num -= t.value;
}
}
return output.toString();
}