Add Java and Python solution for problem liuyubobobo#22

0022-Generate-Parentheses/java-0022/src/Solution1.java

@@ -0,0 +1,40 @@
+/// Source : https://leetcode.com/problems/generate-parentheses/
+/// Author : penpenps
+/// Time   : 2019-05-28
+
+import java.util.*;
+
+/// Recursive with "(" and ")" separately and guarantee open and close num is equal
+/// Time Complexity: O(2^n)
+/// Space Complexity: O(n)
+
+public class Solution1 {
+    public void helper(List<String> ans, String str, int open, int close, int max) {
+        if(str.length() == 2*max){
+            ans.add(str);
+            return;
+        }
+
+        if(open < max)
+            helper(ans, str+"(", open+1, close, max);
+        if(close < open)
+            helper(ans, str+")", open, close+1, max);
+    }
+    public List<String> generateParenthesis(int n) {
+        List<String> ans = new ArrayList<>();
+        helper(ans, "", 0, 0, n);
+        return ans;
+    }
+
+    private static void printList(List<String> list){
+        for(String e: list)
+            System.out.print(e + " ");
+        System.out.println();
+    }
+
+    public static void main(String[] args) {
+        int n = 3;
+        List<String> res = (new Solution1()).generateParenthesis(n);
+        printList(res);
+    }
+}

0022-Generate-Parentheses/python-0022/Solution1.py

@@ -0,0 +1,29 @@
+# Source : https://leetcode.com/problems/generate-parentheses/
+# Author : penpenps
+# Time   : 2019-05-28
+
+from typing import List
+
+# Recursive with "(" and ")" separately and guarantee open and close num is equal
+# Time Complexity: O(2^n)
+# Space Complexity: O(n)
+
+class Solution:
+    def generateParenthesis(self, n: int) -> List[str]:
+        def helper(current, openNum, closeNum, n, ans):
+            if len(current) == 2*n:
+                ans.append(current)
+                return
+            if openNum < n:
+                helper(current+"(", openNum + 1, closeNum, n, ans)
+            if closeNum < openNum:
+                helper(current+")", openNum, closeNum + 1, n, ans)
+
+        ans = []
+        helper("", 0, 0, n, ans)
+        return ans
+
+if __name__ == '__main__':
+	solution = Solution()
+	n = 3
+	print(solution.generateParenthesis(n))

readme.md

@@ -66,7 +66,7 @@ email: [[email protected]](mailto:[email protected])
 | 019 | [Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/description/) | [solution](https://leetcode.com/problems/remove-nth-node-from-end-of-list/solution/) | [C++](0019-Remove-Nth-Node-From-End-of-List/cpp-0019/) | [Java](0019-Remove-Nth-Node-From-End-of-List/java-0019/src/) | |
 | 020 | [Valid Parentheses](https://leetcode.com/problems/valid-parentheses/description/) | [solution](https://leetcode.com/problems/valid-parentheses/solution/) | [C++](0020-Valid-Parentheses/cpp-0020/) | [Java](0020-Valid-Parentheses/java-0020/src/) | |
 | 021 | [Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/description/) | [solution](https://leetcode.com/problems/merge-two-sorted-lists/solution/) | [C++](0021-Merge-Two-Sorted-Lists/cpp-0021/) | | |
-| 022 | [Generate Parentheses](https://leetcode.com/problems/generate-parentheses/description/) | [solution](https://leetcode.com/problems/generate-parentheses/solution/) | [C++](0022-Generate-Parentheses/cpp-0022/) | | |
+| 022 | [Generate Parentheses](https://leetcode.com/problems/generate-parentheses/description/) | [solution](https://leetcode.com/problems/generate-parentheses/solution/) | [C++](0022-Generate-Parentheses/cpp-0022/) | [Java](0022-Generate-Parentheses/java-0022/) | [Python](0022-Generate-Parentheses/python-0022/) |
 | 023 | [Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/description/) | [solution](https://leetcode.com/problems/merge-k-sorted-lists/solution/) | [C++](0023-Merge-k-Sorted-Lists/cpp-0023/) | | |
 | 024 | [Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/description/) | [无] | [C++](0024-Swap-Nodes-in-Pairs/cpp-0024/) | [Java](0024-Swap-Nodes-in-Pairs/java-0024/src/) | |
 | 025 | [Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/description/) | [无] | [C++](0025-Reverse-Nodes-in-k-Group/cpp-0025/) | | |