12. Integer to Roman

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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();}

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