From 9977fb5996d2e593d0bc220754d91c0abeec181f Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Wed, 19 Oct 2022 21:47:25 +0200 Subject: [PATCH 1/3] =?UTF-8?q?=E6=9B=B4=E6=96=B0=20541.=20=E5=8F=8D?= =?UTF-8?q?=E8=BD=AC=E5=AD=97=E7=AC=A6=E4=B8=B2II=EF=BC=8C=20=E6=8F=90?= =?UTF-8?q?=E4=BE=9Bscala=E7=89=88=E6=9C=AC=E7=9A=84=E9=80=92=E5=BD=92?= =?UTF-8?q?=E8=A7=A3=E6=B3=95?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0541.反转字符串II.md | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 3dd6b1e8..02ad92a0 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -412,6 +412,26 @@ object Solution { } ``` +版本三: (递归) +```scala +import scala.annotation.tailrec + +object Solution { + def reverseStr(s: String, k: Int): String = { + @tailrec // 这个函数已经优化成了尾递归 + def reverse(s: String, needToReverse: Boolean, history: String): String = { + // 截取前k个字符（判断是否翻转） + val subStr = if (needToReverse) s.take(k).reverse else s.take(k) + // 如果字符串长度小于k，返回结果 + // 否则，对于剩余字符串进行同样的操作 + if (s.length < k) history + subStr + else reverse(s.drop(k), !needToReverse, history + subStr) + } + reverse(s, true, "") + } +} +``` + Rust: ```Rust From 77b431d27618a202d90b5bfc420b6686cbc66312 Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Wed, 19 Oct 2022 22:20:01 +0200 Subject: [PATCH 2/3] =?UTF-8?q?Update=200541.=E5=8F=8D=E8=BD=AC=E5=AD=97?= =?UTF-8?q?=E7=AC=A6=E4=B8=B2II.md?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0541.反转字符串II.md | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index 02ad92a0..f38ac042 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -399,14 +399,17 @@ object Solution { } } ``` -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 +版本二: 首先利用grouped每隔k个进行分割，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 { +object SolutionFunc { 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) + // s = "abcdefg", k = 2 + s.grouped(k) // Iterator ["ab", "cd", "ef", "g"] + .zipWithIndex // Iterator [("ab", 0), ("cd", 1), ("ef", 2), ("g", 3)] + .map { + case (subStr, index) => + if (index % 2 == 0) subStr.reverse else subStr + } .mkString } } From 7278b038c680d960d2c7d4858cb836144b90ea1c Mon Sep 17 00:00:00 2001 From: Jijie LIU Date: Wed, 19 Oct 2022 22:23:50 +0200 Subject: [PATCH 3/3] rename the object class name of Scala Solution 2 --- problems/0541.反转字符串II.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/problems/0541.反转字符串II.md b/problems/0541.反转字符串II.md index f38ac042..238e6349 100644 --- a/problems/0541.反转字符串II.md +++ b/problems/0541.反转字符串II.md @@ -401,7 +401,7 @@ object Solution { ``` 版本二: 首先利用grouped每隔k个进行分割，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 SolutionFunc { +object Solution { def reverseStr(s: String, k: Int): String = { // s = "abcdefg", k = 2 s.grouped(k) // Iterator ["ab", "cd", "ef", "g"]