diff --git a/clojure/12.clj b/clojure/12.clj
deleted file mode 100644
index 8933337..0000000
--- a/clojure/12.clj
+++ /dev/null
@@ -1,45 +0,0 @@
-(ns clojure.12
-  "Leetcode: 12\n
-   Name: Integer to Roman\n"
-  (:require [clojure.test :refer [deftest is run-tests]]))
-
-(defonce roman-symbols 
-  [["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]])
-
-(defn int-to-roman 
-  "Convert an integer to its Roman numeral representation.
-    
-    Args:
-      num - An integer value to convert (1 <= num <= 3999).
-    
-    Returns:
-      A string representing the Roman numeral equivalent of the integer.
-    
-    Examples:
-      (int-to-roman 4)    ;=> \"IV\"
-      (int-to-roman 9)    ;=> \"IX\"
-      (int-to-roman 1994) ;=> \"MCMXCIV\""
-  [num]
-  {:pre [(and (integer? num) (<= 1 num 3999))]}
-  (loop [number num
-         result ""]
-    (if (zero? number)
-      result
-      (let [[symbol value] (first (filter #(<= (second %) number) roman-symbols))]
-        (recur (- number value)
-               (str result symbol))))))
-
-(deftest test-int-to-roman
-  (is (= (int-to-roman 1) "I"))
-  (is (= (int-to-roman 4) "IV"))
-  (is (= (int-to-roman 9) "IX"))
-  (is (= (int-to-roman 58) "LVIII"))
-  (is (= (int-to-roman 1994) "MCMXCIV"))
-  (is (= (int-to-roman 3999) "MMMCMXCIX"))
-  (is (= (int-to-roman 1) "I"))
-  (is (= (int-to-roman 3999) "MMMCMXCIX"))
-  (is (thrown? AssertionError (int-to-roman 0)))
-  (is (thrown? AssertionError (int-to-roman 4000))))
-
-(run-tests)
diff --git a/solutions/0001-0100/0012-integer-to-roman/README.md b/solutions/0001-0100/0012-integer-to-roman/README.md
new file mode 100644
index 0000000..f639646
--- /dev/null
+++ b/solutions/0001-0100/0012-integer-to-roman/README.md
@@ -0,0 +1,12 @@
+# 12. Integer to Roman
+
+[LeetCode problem 12](https://leetcode.com/problems/integer-to-roman/)
+
+- **Difficulty**: Medium
+- **Tags**: hash-table, math, string, greedy
+
+## Description
+
+Given an integer in the range `[1, 3999]`, convert it to a Roman numeral,
+handling the six subtractive pairs (`IV`, `IX`, `XL`, `XC`, `CD`, `CM`) that
+Roman numerals use in place of four repeated symbols in a row.
diff --git a/solutions/0001-0100/0012-integer-to-roman/solution.cpp b/solutions/0001-0100/0012-integer-to-roman/solution.cpp
new file mode 100644
index 0000000..49bb2aa
--- /dev/null
+++ b/solutions/0001-0100/0012-integer-to-roman/solution.cpp
@@ -0,0 +1,37 @@
+#include "solution.hpp"
+
+#include <array>
+#include <utility>
+
+namespace leetcode::p0012 {
+
+std::string solve(int num) {
+    static constexpr std::array<std::pair<int, const char*>, 13> romanSymbols{{
+        {1000, "M"},
+        {900, "CM"},
+        {500, "D"},
+        {400, "CD"},
+        {100, "C"},
+        {90, "XC"},
+        {50, "L"},
+        {40, "XL"},
+        {10, "X"},
+        {9, "IX"},
+        {5, "V"},
+        {4, "IV"},
+        {1, "I"},
+    }};
+
+    std::string result;
+
+    for (const auto& [value, symbol] : romanSymbols) {
+        while (num >= value) {
+            result += symbol;
+            num -= value;
+        }
+    }
+
+    return result;
+}
+
+} // namespace leetcode::p0012
diff --git a/solutions/0001-0100/0012-integer-to-roman/solution.hpp b/solutions/0001-0100/0012-integer-to-roman/solution.hpp
new file mode 100644
index 0000000..cc2f7a2
--- /dev/null
+++ b/solutions/0001-0100/0012-integer-to-roman/solution.hpp
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <string>
+
+namespace leetcode::p0012 {
+
+// optimized: O(1) time (13 fixed symbols), O(1) space — greedy, largest
+// symbol first.
+std::string solve(int num);
+
+} // namespace leetcode::p0012
diff --git a/solutions/0001-0100/0012-integer-to-roman/test.cpp b/solutions/0001-0100/0012-integer-to-roman/test.cpp
new file mode 100644
index 0000000..c5f789d
--- /dev/null
+++ b/solutions/0001-0100/0012-integer-to-roman/test.cpp
@@ -0,0 +1,12 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "solution.hpp"
+
+TEST_CASE("Problem 12", "[p0012]") {
+    CHECK(leetcode::p0012::solve(1) == "I");
+    CHECK(leetcode::p0012::solve(4) == "IV");
+    CHECK(leetcode::p0012::solve(9) == "IX");
+    CHECK(leetcode::p0012::solve(58) == "LVIII");
+    CHECK(leetcode::p0012::solve(1994) == "MCMXCIV");
+    CHECK(leetcode::p0012::solve(3999) == "MMMCMXCIX");
+}
diff --git a/swift/12.swift b/swift/12.swift
deleted file mode 100644
index 59f6cfb..0000000
--- a/swift/12.swift
+++ /dev/null
@@ -1,31 +0,0 @@
-class Solution {
-    func intToRoman(_ num: Int) -> String {
-        let romanSymbols = [
-            ("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)
-        ]
-        
-        var number = num
-        var result = ""
-        
-        for (symbol, value) in romanSymbols {
-            while number >= value {
-                result += symbol
-                number -= value
-            }
-        }
-        
-        return result
-    }
-}