[Math] Add solution to Integer to Roman

Math/IntegerToRoman.swift

@@ -0,0 +1,33 @@
+/**
+ * Question Link: https://leetcode.com/problems/integer-to-roman/
+ * Primary idea: Add symbols from big to small, minus relative number as well
+ * Time Complexity: O(n), Space Complexity: O(1)
+ *
+ */
+
+ class IntegerToRoman {
+    func intToRoman(_ num: Int) -> String {
+        guard num > 0 else {
+            return ""
+        }
+
+        let nums = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
+        let symbols = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]
+        var res = ""
+        var digit = 0
+        var number = num
+
+        while number > 0 {
+            let current = number / nums[digit]
+
+            for _ in 0 ..< current {
+                res += symbols[digit]
+            }
+
+            number -= current * nums[digit]
+            digit += 1
+        }
+
+        return res
+    }
+}