Merge pull request doocs#88 from bluesword12350/master

022. Generate Parentheses (java)

Author: yanglbme

solution/022. Generate Parentheses/Solution.java

@@ -0,0 +1,21 @@
+class Solution {
+	List<String> result = new ArrayList<>();
+    public List<String> generateParenthesis(int n) {
+        generateParenthesis(n, n, new char[n * 2], 0);
+        return result;
+    }
+    void generateParenthesis(int left, int right, char[] cache, int index) {
+        if (right == 0) {
+            result.add(String.valueOf(cache));
+            return;
+        }
+        if (left > 0) {
+            cache[index] = '(';
+            generateParenthesis(left - 1, right, cache, index + 1);
+        }
+        if (right > left) {
+            cache[index] = ')';
+            generateParenthesis(left, right - 1, cache, index + 1);
+        }
+    }
+}