Merge pull request youngyangyang04#1329 from wzqwtt/patch10

添加（0344.反转字符串、0541.反转字符串II、剑指Offer05.替换空格）Scala版本

Author: youngyangyang04

problems/0344.反转字符串.md

@@ -266,6 +266,20 @@ public class Solution
     }
 }
 ```
-
+Scala:
+```scala
+object Solution {
+  def reverseString(s: Array[Char]): Unit = {
+    var (left, right) = (0, s.length - 1)
+    while (left < right) {
+      var tmp = s(left)
+      s(left) = s(right)
+      s(right) = tmp
+      left += 1
+      right -= 1
+    }
+  }
+}
+```
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 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/0541.反转字符串II.md

@@ -347,6 +347,47 @@ public class Solution
     }
 }
 ```
-
+Scala:
+
+版本一: (正常解法)
+```scala
+object Solution {
+  def reverseStr(s: String, k: Int): String = {
+    val res = s.toCharArray // 转换为Array好处理
+    for (i <- s.indices by 2 * k) {
+      // 如果i+k大于了res的长度，则需要全部翻转
+      if (i + k > res.length) {
+        reverse(res, i, s.length - 1)
+      } else {
+        reverse(res, i, i + k - 1)
+      }
+    }
+    new String(res)
+  }
+  // 翻转字符串，从start到end
+  def reverse(s: Array[Char], start: Int, end: Int): Unit = {
+    var (left, right) = (start, end)
+    while (left < right) {
+      var tmp = s(left)
+      s(left) = s(right)
+      s(right) = tmp
+      left += 1
+      right -= 1
+    }
+  }
+}
+```
+版本二: 首先利用sliding每隔k个进行分割，随后转换为数组，再使用zipWithIndex添加每个数组的索引，紧接着利用map做变换，如果索引%2==0则说明需要翻转，否则原封不动，最后再转换为String
+```scala
+object Solution {
+  def reverseStr(s: String, k: Int): String = {
+    s.sliding(k, k)
+      .toArray
+      .zipWithIndex
+      .map(v => if (v._2 % 2 == 0) v._1.reverse else v._1)
+      .mkString
+  }
+}
+```
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

problems/剑指Offer05.替换空格.md

@@ -413,8 +413,62 @@ func replaceSpace(_ s: String) -> String {
 }
 ```
 
+Scala:
 
-
+方式一: 双指针
+```scala
+object Solution {
+  def replaceSpace(s: String): String = {
+    var count = 0
+    s.foreach(c => if (c == ' ') count += 1) // 统计空格的数量
+    val sOldSize = s.length // 旧数组字符串长度
+    val sNewSize = s.length + count * 2 // 新数组字符串长度
+    val res = new Array[Char](sNewSize) // 新数组
+    var index = sNewSize - 1 // 新数组索引
+    // 逆序遍历
+    for (i <- (0 until sOldSize).reverse) {
+      if (s(i) == ' ') {
+        res(index) = '0'
+        index -= 1
+        res(index) = '2'
+        index -= 1
+        res(index) = '%'
+      } else {
+        res(index) = s(i)
+      }
+      index -= 1
+    }
+    res.mkString
+  }
+}
+```
+方式二: 使用一个集合，遇到空格就添加%20
+```scala
+object Solution {
+  import scala.collection.mutable.ListBuffer
+  def replaceSpace(s: String): String = {
+    val res: ListBuffer[Char] = ListBuffer[Char]()
+    for (i <- s.indices) {
+      if (s(i) == ' ') {
+        res += '%'
+        res += '2'
+        res += '0'
+      }else{
+        res += s(i)
+      }
+    }
+    res.mkString
+  }
+}
+```
+方式三: 使用map
+```scala
+object Solution {
+  def replaceSpace(s: String): String = {
+    s.map(c => if(c == ' ') "%20" else c).mkString
+  }
+}
+```
 
 
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