Add solution #856

Author: JoshCrozier

README.md

@@ -663,6 +663,7 @@
 853|[Car Fleet](./0853-car-fleet.js)|Medium|
 854|[K-Similar Strings](./0854-k-similar-strings.js)|Hard|
 855|[Exam Room](./0855-exam-room.js)|Medium|
+856|[Score of Parentheses](./0856-score-of-parentheses.js)|Medium|
 867|[Transpose Matrix](./0867-transpose-matrix.js)|Easy|
 868|[Binary Gap](./0868-binary-gap.js)|Easy|
 872|[Leaf-Similar Trees](./0872-leaf-similar-trees.js)|Easy|

solutions/0856-score-of-parentheses.js

@@ -0,0 +1,31 @@
+/**
+ * 856. Score of Parentheses
+ * https://leetcode.com/problems/score-of-parentheses/
+ * Difficulty: Medium
+ *
+ * Given a balanced parentheses string s, return the score of the string.
+ *
+ * The score of a balanced parentheses string is based on the following rule:
+ * - "()" has score 1.
+ * - AB has score A + B, where A and B are balanced parentheses strings.
+ * - (A) has score 2 * A, where A is a balanced parentheses string.
+ */
+
+/**
+ * @param {string} s
+ * @return {number}
+ */
+var scoreOfParentheses = function(s) {
+  const stack = [0];
+
+  for (const char of s) {
+    if (char === '(') {
+      stack.push(0);
+    } else {
+      const value = stack.pop();
+      stack[stack.length - 1] += Math.max(2 * value, 1);
+    }
+  }
+
+  return stack[0];
+};