Time: 0 ms (100.00%) | Memory: 43 MB (71.01%) - LeetSync

Author: jagrit007

22-generate-parentheses/generate-parentheses.java

@@ -0,0 +1,29 @@
+import java.util.ArrayList;
+import java.util.List;
+
+class Solution {
+    public List<String> generateParenthesis(int n) {
+        List<String> result = new ArrayList<>();
+        StringBuilder intermediate = new StringBuilder(2 * n);
+
+        helper(intermediate, 0, 0, n, result);
+        return result;
+    }
+
+    private void helper(StringBuilder intermediate, int left, int right, int n, List<String> result) {
+        if (intermediate.length() == 2 * n) {
+            result.add(intermediate.toString());
+            return;
+        }
+        if (left < n) {
+            intermediate.append('(');
+            helper(intermediate, left + 1, right, n, result);
+            intermediate.setLength(intermediate.length() - 1);
+        }
+        if (right < left) {
+            intermediate.append(')');
+            helper(intermediate, left, right + 1, n, result);
+            intermediate.setLength(intermediate.length() - 1);
+        }
+    }
+}