refactor 856

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_856.java

@@ -1,10 +1,31 @@
 package com.fishercoder.solutions;
 
+import java.util.Stack;
+
 public class _856 {
     public static class Solution1 {
-        //TODO: implement it
+        /**
+         * credit: https://leetcode.com/problems/score-of-parentheses/discuss/141763/Java-solution-using-Stack
+         */
         public int scoreOfParentheses(String S) {
-            return -1;
+            Stack<Integer> stack = new Stack<>();
+            for (int i = 0; i < S.length(); i++) {
+                if (S.charAt(i) == '(') {
+                    stack.push(-1);
+                } else {
+                    int curr = 0;
+                    while (stack.peek() != -1) {
+                        curr += stack.pop();
+                    }
+                    stack.pop();
+                    stack.push(curr == 0 ? 1 : curr * 2);
+                }
+            }
+            int score = 0;
+            while (!stack.isEmpty()) {
+                score += stack.pop();
+            }
+            return score;
         }
     }
 }

src/test/java/com/fishercoder/_856Test.java

@@ -7,7 +7,6 @@
 
 import static org.junit.Assert.assertEquals;
 
-@Ignore
 public class _856Test {
     private static _856.Solution1 solution1;