Scala中的阵列旋转

女爷i 2023-03-05 09:49 36阅读 0赞

### 阵列旋转 **(**Array Rotation**)** ###

**Array rotation** is the process of shifting elements of the array in a specific direction and rotate the last element to first or first to last based on the direction of rotation of the array.

**数组旋转**是在特定方向上移动数组元素，并根据数组旋转的方向将最后一个元素旋转到第一个或第一个到最后一个过程。

If you need some basic information on arrays in Scala please read here: [ Arrays in Scala][Arrays in Scala].

如果您需要有关Scala中数组的一些基本信息，请阅读此处： [Scala中的数组][Arrays in Scala] 。

There are two **types of array rotation**:

**数组旋转**有两种**类型** ：

1.  **Lift Shift**: Leftward shifting of elements from index n to n-1, and shift element at the first index to the last index.
    
    **提升移位** ：元素从索引n向左移位到n-1，然后将第一个索引处的元素移位到最后一个索引。
2.  **Right Shift**: Rightward shifting of elements from index n-1 to n, and shift element at last index to the first index.
    
    **右移** ：将元素从索引n-1向右移至n，并将最后一个索引的元素移至第一个索引。

**Example:**

**例：**

Array: {2, 5, 7, 9, 1, 3}
        Left shifted array: {5, 7, 9, 1, 3, 2}
        Right shifted array: {3, 2, 5, 7, 9, 1}

Now, to left rotate array by *n* elements, we will first store the last element of the array in a temporary variable. And run a loop from last to first. And copy element at the *n-1* position to *n* and so on.

现在，要向左旋转数组*n个*元素，我们将首先将数组的最后一个元素存储在一个临时变量中。 并从最后到第一个运行循环。 并将元素在*n-1*位置复制到*n* ，依此类推。

**Program:**

**程序：**

object MyClass {
        
        def rotateArray(A: Array[Int], K: Int): Array[Int] = {
        
            if (A.isEmpty) A
            else rotate(A.toList, K).toArray
        }
        
        def rotateStepwise(l: List[Int]) = {
        
            l.take(l.size - 1).+:(l.last)
        }
        
        def rotate(l: List[Int], K: Int): List[Int] = {
        
          if (K == 0) l
          else rotate(rotateStepwise(l), K - 1)
        }
        
        def main(args: Array[String]) {
        
            var arr = Array(1, 5, 6, 8, 12, 7)
            print("Initial Array : ")
            for(i <- 0 to arr.length-1){
        
                print(arr(i)+" ")
            }
            println()
            var a = rotateArray(arr, 1)
            print("Array after right rotation : ")
            for(i <- 0 to a.length-1){
        
                print(a(i)+" ")
            }
        }
    }

**Output**

**输出量**

Initial Array : 1 5 6 8 12 7 
    Array after right rotation : 7 1 5 6 8 12

**Explanation:**

**说明：**

In this above code, we have a function that is used to right **rotate an array** by *k* steps. The function calls another function which does the rotation work. The function calls a function to rotate the array single step *k* times. ** **

在上面的代码中，我们有一个函数，用于将**数组**右**旋转** *k*步。 该函数调用执行旋转工作的另一个函数。 该函数调用一个函数将数组单步旋转*k*次。 ** **

> 翻译自: [https://www.includehelp.com/scala/array-rotation-in-scala.aspx][https_www.includehelp.com_scala_array-rotation-in-scala.aspx]

[Arrays in Scala]: https://www.includehelp.com/scala/arrays-in-scala.aspx
[https_www.includehelp.com_scala_array-rotation-in-scala.aspx]: https://www.includehelp.com/scala/array-rotation-in-scala.aspx