diff --git a/problems/0344.反转字符串.md b/problems/0344.反转字符串.md index 58bada05..e1f27bd7 100644 --- a/problems/0344.反转字符串.md +++ b/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 + } + } +} +``` -----------------------
diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 8c13a390..99d6ebe0 100644 --- a/problems/0541.反转字符串II.md +++ b/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 + } +} +``` -----------------------
diff --git a/problems/剑指Offer05.替换空格.md b/problems/剑指Offer05.替换空格.md index 037bd427..eecd7f0c 100644 --- a/problems/剑指Offer05.替换空格.md +++ b/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 + } +} +``` -----------------------