Add 12

Author: ChienkuChen

src/_12/12.integer-to-roman.java

@@ -0,0 +1,54 @@
+package _12;
+
+class Solution {
+    public String intToRoman(int num) {
+        int[] values = new int[]{1000, 500, 100, 50, 10, 5, 1};
+        char[] symbols = new char[]{'M', 'D', 'C', 'L', 'X', 'V', 'I'};
+
+        StringBuilder stringBuilder = new StringBuilder();
+
+        for (int i = 0; i < values.length; i += 2) {
+            if (values[i] > num)
+                continue;
+
+            int tmp = num / values[i];
+
+            if (1 <= tmp && tmp <= 3) {
+                while (tmp != 0) {
+                    stringBuilder.append(symbols[i]);
+                    num -= values[i];
+                    tmp--;
+                }
+            } else if (tmp == 4) {
+                stringBuilder.append(symbols[i]).append(symbols[i - 1]);
+                num -= values[i - 1];
+                num += values[i];
+
+            } else if (5 <= tmp && tmp <= 8) {
+                stringBuilder.append(symbols[i - 1]);
+                num -= values[i - 1];
+
+                tmp -= 5;
+                while (tmp != 0) {
+                    stringBuilder.append(symbols[i]);
+                    num -= values[i];
+                    tmp--;
+                }
+            } else if (tmp == 9) {
+                stringBuilder.append(symbols[i]).append(symbols[i - 2]);
+                num -= values[i - 2];
+                num += values[i];
+            }
+        }
+
+        return stringBuilder.toString();
+    }
+
+    public static void main(String[] args) {
+        System.out.println(new Solution().intToRoman(3));
+        System.out.println(new Solution().intToRoman(4));
+        System.out.println(new Solution().intToRoman(9));
+        System.out.println(new Solution().intToRoman(58));
+        System.out.println(new Solution().intToRoman(1994));
+    }
+}