solve problem Generate Parentheses

Author: P-ppc

README.md

@@ -199,6 +199,7 @@ All solutions will be accepted!
 |867|[Transpose Matrix](https://leetcode-cn.com/problems/transpose-matrix/description/)|[java/py/js](./algorithms/TransposeMatrix)|Easy|
 |479|[Largest Palindrome Product](https://leetcode-cn.com/problems/largest-palindrome-product/description/)|[java/py/js](./algorithms/LargestPalindromeProduct)|Easy|
 |102|[Binray Tree Level Order Traversal](https://leetcode-cn.com/problems/binary-tree-level-order-traversal/description/)|[java/py/js](./algorithms/BinrayTreeLevelOrderTraversal)|Medium|
+|22|[Generate Parentheses](https://leetcode-cn.com/problems/generate-parentheses/description/)|[java/py/js](./algorithms/GenerateParentheses)|Easy|
 
 # Database
 |#|Title|Solution|Difficulty|

algorithms/GenerateParentheses/README.md

@@ -0,0 +1,2 @@
+# Generate Parentheses
+This problem can solve by Backtracking Algorithm

algorithms/GenerateParentheses/Solution.java

@@ -0,0 +1,20 @@
+class Solution {
+    public List<String> generateParenthesis(int n) {
+        List<String> res = new ArrayList<String>();
+        backTrack("", n, n, res);
+        return res;
+    }
+    
+    public void backTrack(String s, int left, int right, List<String> res) {
+        if (left == 0 && right == 0) {
+            res.add(s);
+            return;
+        }
+        if (left > 0) {
+            backTrack(s + "(", left - 1, right, res);
+        }
+        if (left < right) {
+            backTrack(s + ")", left, right - 1, res);
+        }
+    }
+}

algorithms/GenerateParentheses/solution.js

@@ -0,0 +1,22 @@
+/**
+ * @param {number} n
+ * @return {string[]}
+ */
+var generateParenthesis = function(n) {
+    let res = []
+    backTrack('', n, n, res)
+    return res
+};
+
+var backTrack = function(s, left, right, res) {
+    if (left === 0 && right === 0) {
+        res.push(s)
+        return
+    }
+    if (left > 0) {
+        backTrack(s + '(', left - 1, right, res)
+    }
+    if (left < right) {
+        backTrack(s + ')', left, right - 1, res)
+    }    
+};

algorithms/GenerateParentheses/solution.py

@@ -0,0 +1,19 @@
+class Solution(object):
+    def generateParenthesis(self, n):
+        """
+        :type n: int
+        :rtype: List[str]
+        """
+        res = []
+        self.backtrack('', n, n, res)
+        return res
+    
+    def backtrack(self, s, left, right, res):
+        if left == 0 and right == 0:
+            res.append(s)
+            return
+        
+        if left > 0:
+            self.backtrack(s + '(', left - 1, right, res)
+        if left < right:
+            self.backtrack(s + ')', left, right - 1, res)