diff --git a/include/s0012_integer_to_roman.hpp b/include/s0012_integer_to_roman.hpp
new file mode 100644
index 0000000..46d773f
--- /dev/null
+++ b/include/s0012_integer_to_roman.hpp
@@ -0,0 +1,13 @@
+#ifndef S0012_INTEGER_TO_ROMAN
+#define S0012_INTEGER_TO_ROMAN
+
+#include <string>
+
+using namespace std;
+
+class Solution {
+ public:
+  string intToRoman(int num);
+};
+
+#endif
diff --git a/src/s0012_integer_to_roman.cpp b/src/s0012_integer_to_roman.cpp
new file mode 100644
index 0000000..bcb0ed5
--- /dev/null
+++ b/src/s0012_integer_to_roman.cpp
@@ -0,0 +1,19 @@
+#include "s0012_integer_to_roman.hpp"
+
+// 贪心哈希表
+// 先硬编码一个哈希表
+// 然后当数值大于一个值的时候，就直接把对应的字符串加上去
+
+string Solution::intToRoman(int num) {
+  int values[] = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
+  string reps[] = {"M",  "CM", "D",  "CD", "C",  "XC", "L",
+                   "XL", "X",  "IX", "V",  "IV", "I"};
+  string res;
+  for (int i = 0; i < 13; i++) {
+    while (num >= values[i]) {
+      num -= values[i];
+      res += reps[i];
+    }
+  }
+  return res;
+}
diff --git a/tests/s0012_integer_to_roman.cpp b/tests/s0012_integer_to_roman.cpp
new file mode 100644
index 0000000..a76d705
--- /dev/null
+++ b/tests/s0012_integer_to_roman.cpp
@@ -0,0 +1,24 @@
+#include "s0012_integer_to_roman.hpp"
+
+#include <gtest/gtest.h>
+
+TEST(Problem12, Case1) {
+  int i{3};
+  string o("III");
+  Solution solution;
+  EXPECT_EQ(solution.intToRoman(i), o);
+}
+
+TEST(Problem12, Case2) {
+  int i{58};
+  string o("LVIII");
+  Solution solution;
+  EXPECT_EQ(solution.intToRoman(i), o);
+}
+
+TEST(Problem12, Case3) {
+  int i{1994};
+  string o("MCMXCIV");
+  Solution solution;
+  EXPECT_EQ(solution.intToRoman(i), o);
+}