[N-0] refactor 12

Author: fishercoder1534

README.md

@@ -655,7 +655,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |15|[3Sum](https://leetcode.com/problems/3sum/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_15.java)|O(n^2)|O(1)|Medium|Two Pointers, Binary Search
 |14|[Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_14.java)| O(n*min(wordLength in this array)) | O(1) | Easy
 |13|[Roman to Integer](https://leetcode.com/problems/roman-to-integer)|[Solution](../master/src/main/java/com/fishercoder/solutions/_13.java)| O(1) | O(1) | Easy
-|12|[Integer to Roman](https://leetcode.com/problems/integer-to-roman/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_12.java)|O(1)|O(1)|Medium|
+|12|[Integer to Roman](https://leetcode.com/problems/integer-to-roman/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_12.java)|O(1)|O(1)|Medium| Math, String
 |11|[Container With Most Water](https://leetcode.com/problems/container-with-most-water/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_11.java)|O(n)|O(1)|Medium|
 |10|[Regular Expression Matching](https://leetcode.com/problems/regular-expression-matching/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_10.java)|O(m*n)|O(m*n)|Hard|DP
 |9|[Palindrome Number](https://leetcode.com/problems/palindrome-number/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_9.java)| O(n) | O(1) | Easy

src/main/java/com/fishercoder/solutions/_12.java

@@ -1,17 +1,21 @@
 package com.fishercoder.solutions;
 
 /**
+ * 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.
  */
 public class _12 {
-    //looked at this post: https://discuss.leetcode.com/topic/12384/simple-solution
-    public String intToRoman(int num) {
-        String[] M = new String[]{"", "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];
+
+    public static class Solution1 {
+        public String intToRoman(int num) {
+            String[] M = new String[]{"", "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];
+        }
     }
 
 }

src/test/java/com/fishercoder/_12Test.java

@@ -0,0 +1,31 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._12;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _12Test {
+    private static _12.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _12.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals("XII", solution1.intToRoman(12));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals("M", solution1.intToRoman(1000));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals("MMMCMXCIX", solution1.intToRoman(3999));
+    }
+}