Merge pull request youngyangyang04#1341 from wzqwtt/patch14

添加（0020.有效的括号、1047.删除字符串中的所有相邻重复项）Scala版本

Author: youngyangyang04

problems/0020.有效的括号.md

@@ -400,6 +400,27 @@ bool isValid(char * s){
     return !stackTop;
 }
 ```
-
+Scala:
+```scala
+object Solution {
+  import scala.collection.mutable
+  def isValid(s: String): Boolean = {
+    if(s.length % 2 != 0) return false    // 如果字符串长度是奇数直接返回false
+    val stack = mutable.Stack[Char]()
+    // 循环遍历字符串
+    for (i <- s.indices) {
+      val c = s(i)
+      if (c == '(' || c == '[' || c == '{') stack.push(c)
+      else if(stack.isEmpty) return false   // 如果没有(、[、{则直接返回false
+      // 以下三种情况，不满足则直接返回false        
+      else if(c==')' && stack.pop() != '(') return false 
+      else if(c==']' && stack.pop() != '[') return false 
+      else if(c=='}' && stack.pop() != '{') return false 
+    }
+    // 如果为空则正确匹配，否则还有余孽就不匹配
+    stack.isEmpty
+  }
+}
+```
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/1047.删除字符串中的所有相邻重复项.md

@@ -374,6 +374,27 @@ func removeDuplicates(_ s: String) -> String {
     return String(stack)
 }
 ```
-
+Scala:
+```scala
+object Solution {
+  import scala.collection.mutable
+  def removeDuplicates(s: String): String = {
+    var stack = mutable.Stack[Int]()
+    var str = "" // 保存最终结果
+    for (i <- s.indices) {
+      var tmp = s(i)
+      // 如果栈非空并且栈顶元素等于当前字符，那么删掉栈顶和字符串最后一个元素
+      if (!stack.isEmpty && tmp == stack.head) {
+        str = str.take(str.length - 1)
+        stack.pop()
+      } else {
+        stack.push(tmp)
+        str += tmp
+      }
+    }
+    str
+  }
+}
+```
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>