12. Integer to Roman

12. Integer to Roman/solution.js

@@ -0,0 +1,70 @@
+/**
+ * @param {number} num
+ * @return {string}
+ */
+ var intToRoman = function(num) {
+    const m = {
+        '1': 'I',
+
+        '2': 'II',
+        '3': 'III',
+
+        '5': 'V',
+
+        '6': 'VI',
+        '7': 'VII',
+        '8': 'VIII',
+
+        '10': 'X',
+        '50': 'L',
+
+        '60': 'LX',
+        '70': 'LXX',
+        '80': 'LXXX',
+
+        '100': 'C',
+        '500': 'D',
+
+        '600': 'DC',
+        '700': 'DCC',
+        '800': 'DCCC',
+
+
+        '1000': 'M',
+        // six instances
+        '4': 'IV',
+        '9': 'IX',
+        '40': 'XL',
+        '90': 'XC',
+        '400': 'CD',
+        '900': 'CM'        
+    }
+
+    if (num > 0 && num < 11)
+        return m[num.toString()]
+
+    const i = m[num.toString()]
+    if (i)
+        return i
+    else {
+        let pow10 = 1000
+        let o = ''
+        while (num) {
+            let n = Math.floor(num / pow10)
+            if (n) {
+                let r = m[(pow10*n).toString()]
+                if (r) {
+                    o += r
+                } else {
+                    r = m[(pow10).toString()]
+                    for (let i = 0; i < n; ++i) {
+                        o += r
+                    }
+                }
+            }
+            num %= pow10
+            pow10 /= 10
+        }
+        return o
+    }
+};