From 4ee707c789e6ba4c4c305ba43f32d3ba952d3cbf Mon Sep 17 00:00:00 2001
From: acicchetti <acicchetti@constantcontact.com>
Date: Thu, 14 Feb 2019 14:02:17 -0500
Subject: [PATCH] Changed implemention to a Stack instead of a List

---
 .../src/main/kotlin/BracketPush.kt            | 62 +++++++++----------
 .../src/test/kotlin/BracketPushTest.kt        |  1 +
 2 files changed, 32 insertions(+), 31 deletions(-)

diff --git a/kotlin/bracket-push/src/main/kotlin/BracketPush.kt b/kotlin/bracket-push/src/main/kotlin/BracketPush.kt
index c2da8bb..31e7362 100644
--- a/kotlin/bracket-push/src/main/kotlin/BracketPush.kt
+++ b/kotlin/bracket-push/src/main/kotlin/BracketPush.kt
@@ -1,32 +1,32 @@
-class BracketPush {
-    companion object {
-        fun isValid(inpString: String): Boolean{
-            val stack = mutableListOf<Char>()
-            val realString = inpString.filter {
-                (it == '{') or
-                (it == '[') or
-                (it == '(') or
-                (it == ')') or
-                (it == ']') or
-                (it == '}') }
-            for (i in realString){
-                if ((i == '{') or
-                        (i == '[') or
-                        (i == '(')){
-                    stack.add(0, i)
-                }
-                else {
-                    val temp = if (stack.size == 0) {'a'} else {stack.removeAt(0)}
-                    when (temp){
-                        '(' -> if (i != ')') return false
-                        '{' -> if (i != '}') return false
-                        '[' -> if (i != ']') return false
-                        else -> return false
-                    }
-                }
-            }
-            return stack.isEmpty()
-        }
-
-    }
+import java.util.Stack
+
+class BracketPush {
+    companion object {
+        fun isValid(inpString: String): Boolean{
+            val stack = Stack<Char>()
+            val realString = inpString.filter {
+                (it == '{') or
+                (it == '[') or
+                (it == '(') or
+                (it == ')') or
+                (it == ']') or
+                (it == '}') }
+            for (i in realString){
+                if ((i == '{') or (i == '[') or (i == '(')){
+                    stack.push(i)
+                }
+                else {
+                    val temp = if (stack.size == 0) {'a'} else {stack.pop()}
+                    when (temp){
+                        '(' -> if (i != ')') return false
+                        '{' -> if (i != '}') return false
+                        '[' -> if (i != ']') return false
+                        else -> return false
+                    }
+                }
+            }
+            return stack.isEmpty()
+        }
+
+    }
 }
\ No newline at end of file
diff --git a/kotlin/bracket-push/src/test/kotlin/BracketPushTest.kt b/kotlin/bracket-push/src/test/kotlin/BracketPushTest.kt
index dcaa6a6..322c27d 100644
--- a/kotlin/bracket-push/src/test/kotlin/BracketPushTest.kt
+++ b/kotlin/bracket-push/src/test/kotlin/BracketPushTest.kt
@@ -23,6 +23,7 @@ class BracketPushTest(val input: String, val expectedOutput: Boolean) {
                 arrayOf("([{])", false),
                 arrayOf("[({]})", false),
                 arrayOf("(((185 + 223.85) * 15) - 543)/2", true),
+                arrayOf("b(())[]", true),
                 arrayOf("\\\\left(\\\\begin{array}{cc} \\\\frac{1}{3} & x\\\\\\\\ \\\\mathrm{e}^{x} &... x^2 \\\\end{array}\\\\right)", true)
         )
     }