013 solved.

0013-Roman-to-Integer/cpp-0013/CMakeLists.txt

@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.5)
+project(cpp_0013)
+
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+
+set(SOURCE_FILES main.cpp)
+add_executable(cpp_0013 ${SOURCE_FILES})

0013-Roman-to-Integer/cpp-0013/main.cpp

@@ -0,0 +1,38 @@
+/// Source : https://leetcode.com/problems/roman-to-integer/description/
+/// Author : liuyubobobo
+/// Time   : 2018-09-17
+
+#include <iostream>
+#include <unordered_map>
+
+using namespace std;
+
+
+/// Ad-Hoc
+/// Time Complexity: O(n)
+/// Space Complexity: O(1)
+class Solution {
+public:
+    int romanToInt(string s) {
+
+        unordered_map<char, int> map = {
+                {'I', 1}, {'V', 5}, {'X', 10}, {'L', 50}, {'C', 100}, {'D', 500}, {'M', 1000}};
+
+        int res = 0;
+        for(int i = 0; i < s.size(); i ++)
+            if(i + 1 < s.size() && map[s[i]] < map[s[i + 1]]){
+                res += map[s[i + 1]] - map[s[i]];
+                i ++;
+            }
+            else
+                res += map[s[i]];
+
+        return res;
+    }
+};
+
+
+int main() {
+
+    return 0;
+}

readme.md

@@ -56,7 +56,7 @@ email: [[email protected]](mailto:[email protected])
 | | | | | | |
 | 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/) | | |
-| | | | | | |
+| 013 | [Roman to Integer](https://leetcode.com/problems/roman-to-integer/description/) | [无] | [C++](0013-Roman-to-Integer/cpp-0013/) | | |
 | 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/) | | |
 | 016 | [3Sum Closest](https://leetcode.com/problems/3sum-closest/description/) | [无] | [C++](0016-3Sum-Closest/cpp-0016/) | | |