0012 solved.

0012-Integer-to-Roman/cpp-0012/CMakeLists.txt

@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.5)
+project(cpp_0012)
+
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+
+set(SOURCE_FILES main.cpp)
+add_executable(cpp_0012 ${SOURCE_FILES})

0012-Integer-to-Roman/cpp-0012/main.cpp

@@ -0,0 +1,48 @@
+/// Source : https://leetcode.com/problems/integer-to-roman/description/
+/// Author : liuyubobobo
+/// Time   : 2018-09-16
+
+#include <iostream>
+#include <cmath>
+
+using namespace std;
+
+
+/// Ad-Hoc
+/// Time Complexity: O(1)
+/// Space Complexity: O(1)
+class Solution {
+public:
+    string intToRoman(int num) {
+
+        string res = "";
+        string one[] = {"I", "X", "C", "M", ""}, five[] = {"V", "L", "D", ""};
+        for(int k = 3; k >= 0; k --){
+            int b = (int)pow(10, k);
+            if(num >= b){
+                int x = num / b;
+                res += rome(x, one[k], five[k], one[k + 1]);
+                num %= b;
+            }
+        }
+        return res;
+    }
+
+private:
+    string rome(int x, string one, string five, string ten){
+        if(x <= 3)
+            return string(x, one[0]);
+        else if(x == 4)
+            return one + five;
+        else if(x <= 8)
+            return five + string(x - 5, one[0]);
+        // x == 9
+        return one + ten;
+    }
+};
+
+
+int main() {
+
+    return 0;
+}

readme.md

@@ -55,6 +55,7 @@ email: [[email protected]](mailto:[email protected])
 | 007 | [Reverse Integer](https://leetcode.com/problems/reverse-integer/description/) | [solution](https://leetcode.com/problems/reverse-integer/solution/) | [C++](0007-Reverse-Integer/cpp-0007/) | | |
 | | | | | | |
 | 011 | [Container With Most Water](https://leetcode.com/problems/container-with-most-water/description/) | [solution](https://leetcode.com/problems/container-with-most-water/solution/) | [C++](0011-Container-With-Most-Water/cpp-0011/) | | |
+| 012 | [Integer to Roman](https://leetcode.com/problems/integer-to-roman/description/) | [无] | [C++](0012-Integer-to-Roman/cpp-0012/) | | |
 | | | | | | |
 | 014 | [Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/description/) | [无] | [C++](0014-Longest-Common-Prefix/cpp-0014/) | | |
 | 015 | [3Sum](https://leetcode.com/problems/3sum/description/) | [无] | [C++](0015-3Sum/cpp-0015/) | | |