Add solution #22

Author: JoshCrozier

README.md

@@ -24,6 +24,7 @@
 19|[Remove Nth Node From End of List](./0019-remove-nth-node-from-end-of-list.js)|Medium|
 20|[Valid Parentheses](./0020-valid-parentheses.js)|Easy|
 21|[Merge Two Sorted Lists](./0021-merge-two-sorted-lists.js)|Easy|
+22|[Generate Parentheses](./0022-generate-parentheses.js)|Medium|
 27|[Remove Element](./0027-remove-element.js)|Easy|
 28|[Implement strStr()](./0028-implement-strstr.js)|Easy|
 31|[Next Permutation](./0031-next-permutation.js)|Medium|

solutions/0022-generate-parentheses.js

@@ -0,0 +1,28 @@
+/**
+ * 22. Generate Parentheses
+ * https://leetcode.com/problems/generate-parentheses/
+ * Difficulty: Medium
+ *
+ * Given n pairs of parentheses, write a function to generate all combinations of
+ * well-formed parentheses.
+ */
+
+/**
+ * @param {number} n
+ * @return {string[]}
+ */
+var generateParenthesis = function(n) {
+  const result = [];
+  backtrack(result, '', 0, 0, n);
+  return result;
+};
+
+function backtrack(result, str, open, close, max) {
+  if (str.length == max * 2){
+    result.push(str);
+    return;
+  }
+
+  if (open < max) backtrack(result, `${str}(`, open + 1, close, max);
+  if (close < open) backtrack(result, `${str})`, open, close + 1, max);
+}