feat: add solutions to lc problem: No.0012

No.0012.Integer to Roman

Author: yanglbme

solution/0000-0099/0012.Integer to Roman/README.md

@@ -192,6 +192,25 @@ function intToRoman(num: number): string {
 }
 ```
 
+### **C#**
+
+```cs
+public class Solution {
+    public string IntToRoman(int num) {
+        List<string> cs = new List<string>{"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
+        List<int> vs = new List<int>{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
+        StringBuilder ans = new StringBuilder();
+        for (int i = 0; i < cs.Count; i++) {
+            while (num >= vs[i]) {
+                ans.Append(cs[i]);
+                num -= vs[i];
+            }
+        }
+        return ans.ToString();
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0012.Integer to Roman/README_EN.md

@@ -62,6 +62,12 @@ M             1000</pre>
 
 ## Solutions
 
+**Approach 1: Greedy**
+
+We can list all possible symbols $cs$ and corresponding values $vs$ first, then enumerate the value $vs[i]$ from large to small, and use the symbol $cs[i]$ as much as possible each time until the number $num$ becomes $0$.
+
+The time complexity is $O(m)$ and the space complexity is $O(m)$, where $m$ is the number of symbols.
+
 <!-- tabs:start -->
 
 ### **Python3**
@@ -167,6 +173,25 @@ function intToRoman(num: number): string {
 }
 ```
 
+### **C#**
+
+```cs
+public class Solution {
+    public string IntToRoman(int num) {
+        List<string> cs = new List<string>{"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
+        List<int> vs = new List<int>{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
+        StringBuilder ans = new StringBuilder();
+        for (int i = 0; i < cs.Count; i++) {
+            while (num >= vs[i]) {
+                ans.Append(cs[i]);
+                num -= vs[i];
+            }
+        }
+        return ans.ToString();
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0012.Integer to Roman/Solution.cs

@@ -0,0 +1,14 @@
+public class Solution {
+    public string IntToRoman(int num) {
+        List<string> cs = new List<string>{"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
+        List<int> vs = new List<int>{1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
+        StringBuilder ans = new StringBuilder();
+        for (int i = 0; i < cs.Count; i++) {
+            while (num >= vs[i]) {
+                ans.Append(cs[i]);
+                num -= vs[i];
+            }
+        }
+        return ans.ToString();
+    }
+}