update 921

Author: fishercoder1534

Diff for: src/main/java/com/fishercoder/solutions/_921.java

@@ -1,20 +1,21 @@
 package com.fishercoder.solutions;
 
-import java.util.Stack;
+import java.util.Deque;
+import java.util.LinkedList;
 
 public class _921 {
     public static class Solution1 {
-        public int minAddToMakeValid(String S) {
-            Stack<Character> stack = new Stack<>();
-            for (char c : S.toCharArray()) {
+        public int minAddToMakeValid(String s) {
+            Deque<Character> stack = new LinkedList<>();
+            for (char c : s.toCharArray()) {
                 if (c == ')') {
-                    if (!stack.isEmpty() && stack.peek() == '(') {
-                        stack.pop();
+                    if (!stack.isEmpty() && stack.peekLast() == '(') {
+                        stack.pollLast();
                     } else {
-                        stack.push(c);
+                        stack.addLast(c);
                     }
                 } else {
-                    stack.push(c);
+                    stack.addLast(c);
                 }
             }
             return stack.size();

Diff for: src/test/java/com/fishercoder/_921Test.java

@@ -1,16 +1,16 @@
 package com.fishercoder;
 
 import com.fishercoder.solutions._921;
-import org.junit.BeforeClass;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class _921Test {
     private static _921.Solution1 solution1;
 
-    @BeforeClass
-    public static void setup() {
+    @BeforeEach
+    public void setup() {
         solution1 = new _921.Solution1();
     }
 
@@ -34,4 +34,9 @@ public void test4() {
         assertEquals(4, solution1.minAddToMakeValid("()))(("));
     }
 
+    @Test
+    public void test5() {
+        assertEquals(1, solution1.minAddToMakeValid(")()"));
+    }
+
 }