blocks|key|4257768|text|为什么不做这样简单的事情呢？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4257769|import+scala.collection.immutable.ArraySeq
import+scala.reflect.ClassTag

def+rotate[T+:+ClassTag](arr:+ArraySeq[T])(pos:+Int):+ArraySeq[T]+=+{
++val+length+=+arr.length
++ArraySeq.tabulate[T](n+=+length)+{+i+=>
++++arr((i+%2B+1+%2B+pos)+%25+length)
++}
}|code-block|syntax|javascript|4257770|它可以像这样使用：|4257771|rotate(arr+=+ArraySeq(1,+2,+3,+4,+5,+6,+7))(pos+=+3)
//+res:+ArraySeq[Int]+=+ArraySeq(,+5,+6,+7,+1,+2,+3,+4)|4257772|4257773|您可以看到运行的代码。|4257774|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|R|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|T|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|U|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|O|$]]

Why not just something as simple as this?
<pre class="lang-scala prettyprint-override"><code>import scala.collection.immutable.ArraySeq
import scala.reflect.ClassTag

def rotate[T : ClassTag](arr: ArraySeq[T])(pos: Int): ArraySeq[T] = {
 val length = arr.length
 ArraySeq.tabulate[T](n = length) { i =&gt;
 arr((i + 1 + pos) % length)
 }
}
</code></pre>
Which can be used like this:
<pre class="lang-scala prettyprint-override"><code>rotate(arr = ArraySeq(1, 2, 3, 4, 5, 6, 7))(pos = 3)
// res: ArraySeq[Int] = ArraySeq(, 5, 6, 7, 1, 2, 3, 4)
</code></pre>
<hr />
You can see the code running <a href="https://scastie.scala-lang.org/BalmungSan/kgao7yHvRn2mPTXIPTSznw/9" rel="nofollow noreferrer">here</a>.

blocks|key|1941050|text|只有当范围从零开始时，您的代码才能工作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1941051|for(i+<-+start+until+end/2)+{
++temp+=+brr(i)
++brr(i)+=+brr(end-i-1)
++brr(end-i-1)+=+temp
}|code-block|syntax|javascript|1941052|应该是这样的：|1941053|for(i+<-+0+until+(end-start)/2)+{
++temp+=+brr(start%2Bi)
++brr(start%2Bi)+=+brr(end-i-1)
++brr(end-i-1)+=+temp
}|1941054|有了这个改变，你的代码就可以工作了。|1941055|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Your code will only work when the range starts at zero.
<pre><code>for(i &lt;- start until end/2) {
 temp = brr(i)
 brr(i) = brr(end-i-1)
 brr(end-i-1) = temp
}
</code></pre>
Should be something like:
<pre><code>for(i &lt;- 0 until (end-start)/2) {
 temp = brr(start+i)
 brr(start+i) = brr(end-i-1)
 brr(end-i-1) = temp
}
</code></pre>
With this change your code works.

blocks|key|4257896|text|突变是要避免的，但如果你必须这样做，递归仍然有用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4257897|def+reversePart[A](arr:+Array[A],+start:+Int,+end:+Int):+Unit+=+{
++def+loop(a:Int,+b:Int):+Unit+=
++++if+(a+<+b)+{
++++++val+temp+=+arr(a)
++++++arr(a)+=+arr(b)
++++++arr(b)+=+temp
++++++loop(a%2B1,+b-1)
++++}
++loop(start+max+0,+end+min+arr.length-1)
}

val+test+=+Array(1,+2,+3,+4,+5,+6,+7)
reversePart(test,+0,+3)+++//Array(4,+3,+2,+1,+5,+6,+7)
reversePart(test,+4,+7)+++//Array(4,+3,+2,+1,+7,+6,+5)
reversePart(test,+-1,+99)+//Array(5,+6,+7,+1,+2,+3,+4)|code-block|syntax|javascript|4257898|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Mutation is to be avoided but, if you must, recursion is still useful.
<pre><code>def reversePart[A](arr: Array[A], start: Int, end: Int): Unit = {
 def loop(a:Int, b:Int): Unit =
 if (a &lt; b) {
 val temp = arr(a)
 arr(a) = arr(b)
 arr(b) = temp
 loop(a+1, b-1)
 }
 loop(start max 0, end min arr.length-1)
}

val test = Array(1, 2, 3, 4, 5, 6, 7)
reversePart(test, 0, 3) //Array(4, 3, 2, 1, 5, 6, 7)
reversePart(test, 4, 7) //Array(4, 3, 2, 1, 7, 6, 5)
reversePart(test, -1, 99) //Array(5, 6, 7, 1, 2, 3, 4)
</code></pre>

blocks|key|4258001|text|我意识到这并没有直接回答您的问题，但为了参考和对稍微不同的方法感兴趣的读者，一种可能性是将其实现为视图。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4258002|在本例中，Rotate实现了逻辑，而IndexedSeqViewRotate将rotate方法作为扩展添加到任何IndexedSeqView中，只要它在作用域中。|offset|length|style|CODE|4258003|在测试中，我将视图物化到Vector中以利用相等性，当然您也可以将它们物化到Array中。|4258004|import+scala.collection.IndexedSeqView
import+scala.collection.IndexedSeqView.SomeIndexedSeqOps

final+class+Rotate[A](underlying:+SomeIndexedSeqOps[A],+n:+Int)+extends+IndexedSeqView[A]+{
++@inline+private+def+rotateIndex(i:+Int):+Int+=+((i+-+n)+%25+length+%2B+length)+%25+length
++override+def+apply(i:+Int):+A+=+underlying(rotateIndex(i))
++override+lazy+val+length:+Int+=+underlying.length
}

final+implicit+class+IndexedSeqViewRotate[A](val+underlying:+IndexedSeqView[A])+extends+AnyVal+{
++def+rotate(n:+Int):+IndexedSeqView[A]+=+new+Rotate(underlying,+n)
}

assert(Array().view.rotate(7).to(Vector)+==+Vector.empty)
assert(Array(1,2,3,4,5,6,7).view.rotate(7).to(Vector)+==+Vector(1,2,3,4,5,6,7))
assert(Array(1,2,3,4,5,6,7).view.rotate(0).to(Vector)+==+Vector(1,2,3,4,5,6,7))
assert(Array(1,2,3,4,5,6,7).view.rotate(1).to(Vector)+==+Vector(7,1,2,3,4,5,6))
assert(Array(1,2,3,4,5,6,7).view.rotate(3).to(Vector)+==+Vector(5,6,7,1,2,3,4))
assert(Array(1,2,3,4,5,6,7).view.rotate(-1).to(Vector)+==+Vector(2,3,4,5,6,7,1))|code-block|syntax|javascript|4258005|您可以尝试使用此代码here+on+Scastie。|4258006|entityMap|0|LINK|mutability|MUTABLE|url|https://scastie.scala-lang.org/stefanobaghino/AC86kODlRLuBr0v8vWzVsA/87^0|0|5|6|I|K|13|6|1K|E|0|C|6|12|5|0|0|A|F|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]|$D|12|E|13|F|G]|$D|14|E|15|F|G]|$D|16|E|17|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|18|8|@$D|19|E|1A|F|G]|$D|1B|E|1C|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|1D|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1E|8|@]|9|@$D|1F|E|1G|1|1H]]|A|$]]|$1|Q|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

I realize this doesn't directly answer your question, but for reference and for readers interested in a slightly different approach, one possibility is to implement this as a view.
In this example, <code>Rotate</code> implements the logic, while <code>IndexedSeqViewRotate</code> adds the <code>rotate</code> method as an extension to any <code>IndexedSeqView</code> as long as it's in scope.
In the tests, I materialized the views into <code>Vector</code>s to take advantage of the equality, but of course you can materialize them into an <code>Array</code> as well.
<pre><code>import scala.collection.IndexedSeqView
import scala.collection.IndexedSeqView.SomeIndexedSeqOps

final class Rotate[A](underlying: SomeIndexedSeqOps[A], n: Int) extends IndexedSeqView[A] {
 @inline private def rotateIndex(i: Int): Int = ((i - n) % length + length) % length
 override def apply(i: Int): A = underlying(rotateIndex(i))
 override lazy val length: Int = underlying.length
}

final implicit class IndexedSeqViewRotate[A](val underlying: IndexedSeqView[A]) extends AnyVal {
 def rotate(n: Int): IndexedSeqView[A] = new Rotate(underlying, n)
}

assert(Array().view.rotate(7).to(Vector) == Vector.empty)
assert(Array(1,2,3,4,5,6,7).view.rotate(7).to(Vector) == Vector(1,2,3,4,5,6,7))
assert(Array(1,2,3,4,5,6,7).view.rotate(0).to(Vector) == Vector(1,2,3,4,5,6,7))
assert(Array(1,2,3,4,5,6,7).view.rotate(1).to(Vector) == Vector(7,1,2,3,4,5,6))
assert(Array(1,2,3,4,5,6,7).view.rotate(3).to(Vector) == Vector(5,6,7,1,2,3,4))
assert(Array(1,2,3,4,5,6,7).view.rotate(-1).to(Vector) == Vector(2,3,4,5,6,7,1))
</code></pre>
You can play around with this code <a href="https://scastie.scala-lang.org/stefanobaghino/AC86kODlRLuBr0v8vWzVsA/87" rel="nofollow noreferrer">here on Scastie</a>.

I am trying to rotate an array from a particular position using array reversal method.
Input array: [1,2,3,4,5,6,7]
d = 3
Output array: [5,6,7,1,2,3,4]
To achieve this I thought of working on the array in three steps.
Step1: Reverse the array from starting position until d =&gt; [4,3,2,1,5,6,7]
Step2: Reverse the array from d till the end of the array =&gt; [4,3,2,1,7,6,5]
Step3: Reverse the complete array from Step2 =&gt; [5,6,7,1,2,3,4]
I haven't followed any functional programming pattern as I want to check the algorithm step by step.
<pre><code> val arr = Array[Int](1, 2, 3, 4, 5, 6, 7)
 def reverseAlgo(brr: Array[Int], start: Int, end: Int): Unit = {
 var temp = 0
 for(i &lt;- start until end/2) {
 temp = brr(i)
 brr(i) = brr(end-i-1)
 brr(end-i-1) = temp
 }
 brr.foreach(println)
 }
</code></pre>
Step1 is working fine:
<pre><code> reverseAlgo(arr, 0, 3)
</code></pre>
Output:
<pre><code>3
2
1
4
5
6
7
</code></pre>
But Step2 is not producing the required output:
<pre><code> reverseAlgo(arr, 3, 7)
</code></pre>
Output:
<pre><code>3
2
1
4
5
6
7
</code></pre>
As you see, the output of the array should be: 3,2,1,7,6,5,4
Since the output from Step2 is incorrect, the final output is also wrong.
Step3:
<pre><code>reverseAlgo(arr, 0, arr.length)
</code></pre>
Output:
<pre><code>7
6
5
4
1
2
3
</code></pre>
Could anyone let me know what is the mistake I am doing here ?

How to rotate an array using array reversal technique?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在尝试使用数组反转方法从特定位置旋转数组。输入数组: 1,2,3,4,5,6,7 d=3输出数组: 5,6,7,1,2,3,4为了实现这一点，我想用三个步骤来处理数组。Step1:将数组从起始位置反转到d => 4,3,2,1,5,6,7 Step2:从d反转数组到数组末尾=> 4,3,2,1,7,6,5 Step...

问如何使用数组反转技术旋转数组？
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问如何使用数组反转技术旋转数组？EN