feat: add solution to lc problem: No.0022 (#4044)

Author: djvelimir

solution/0000-0099/0022.Generate Parentheses/README.md

@@ -225,6 +225,33 @@ var generateParenthesis = function (n) {
 };
 ```
 
+#### C#
+
+```cs
+public class Solution {
+    private List<string> ans = new List<string>();
+    private int n;
+
+    public List<string> GenerateParenthesis(int n) {
+        this.n = n;
+        Dfs(0, 0, "");
+        return ans;
+    }
+
+    private void Dfs(int l, int r, string t) {
+        if (l > n || r > n || l < r) {
+            return;
+        }
+        if (l == n && r == n) {
+            ans.Add(t);
+            return;
+        }
+        Dfs(l + 1, r, t + "(");
+        Dfs(l, r + 1, t + ")");
+    }
+}
+```
+
 #### PHP
 
 ```php

solution/0000-0099/0022.Generate Parentheses/README_EN.md

@@ -220,6 +220,33 @@ var generateParenthesis = function (n) {
 };
 ```
 
+#### C#
+
+```cs
+public class Solution {
+    private List<string> ans = new List<string>();
+    private int n;
+
+    public List<string> GenerateParenthesis(int n) {
+        this.n = n;
+        Dfs(0, 0, "");
+        return ans;
+    }
+
+    private void Dfs(int l, int r, string t) {
+        if (l > n || r > n || l < r) {
+            return;
+        }
+        if (l == n && r == n) {
+            ans.Add(t);
+            return;
+        }
+        Dfs(l + 1, r, t + "(");
+        Dfs(l, r + 1, t + ")");
+    }
+}
+```
+
 #### PHP
 
 ```php

solution/0000-0099/0022.Generate Parentheses/Solution.cs

@@ -0,0 +1,22 @@
+public class Solution {
+    private List<string> ans = new List<string>();
+    private int n;
+
+    public List<string> GenerateParenthesis(int n) {
+        this.n = n;
+        Dfs(0, 0, "");
+        return ans;
+    }
+
+    private void Dfs(int l, int r, string t) {
+        if (l > n || r > n || l < r) {
+            return;
+        }
+        if (l == n && r == n) {
+            ans.Add(t);
+            return;
+        }
+        Dfs(l + 1, r, t + "(");
+        Dfs(l, r + 1, t + ")");
+    }
+}