寻找简单移动平均线的程序 |第 2 组

简单移动平均线是从某个 t 时间段的数据中获得的平均值。在正常平均值中，它的值会随着数据的变化而变化，但在这种类型的平均值中，它也会随着时间间隔而变化。我们得到某个时期 t 的平均值，然后我们删除一些以前的数据。我们再次得到新的平均值，并且这个过程继续进行。这就是为什么它是移动平均线。这在金融市场上有很大的应用。或者，这可以简单地可视化如下。

给定一个大小为N的arr[] ，仅包含正整数和一个整数K 。任务是计算前K个元素的简单移动平均值。

例子：

Input: { 1, 3, 5, 6, 8 }, K = 3
Output: 0.33 1.33 3.00 4.67 6.33
Explanation: New number added is 1.0, SMA = 0.33
New number added is 3.0, SMA = 1.33
New number added is 5.0, SMA = 3.0
New number added is 6.0, SMA = 4.67
New number added is 8.0, SMA = 6.33        

Input: Array[]= {2, 5, 7, 3, 11, 9, 13, 12}, K = 2
Output: 1.0 3.5 6 5 7 10 11 12.5

天真的方法：这使用两个嵌套循环。外循环从左到右遍历数组。内循环计算每个索引的K个先前元素的平均值，包括它自己。最后，打印移动平均值。外循环从索引 K 本身开始遍历。我们可以直接显示输出，而不是存储结果，以避免使用额外的空格。

时间复杂度： O(N*K)
空间复杂度： O(1)

高效方法：本问题的Set-1中讨论了有效方法。

空间优化方法：这使用滑动窗口来提高时间效率和空间优化。大小为K的窗口从索引 K 开始，然后为每个索引打印移动平均值。

下面是上述方法的实现。

C++

// C++ code to find the simple moving average
#include 
#include 
using namespace std;
 
// Function to compute moving average
// of previous K elements
void ComputeMovingAverage(int arr[], int N,
                          int K)
{
    int i;
    float sum = 0;
 
    // Initial sum of K elements.
    for (i = 0; i < K; i++) {
        sum += arr[i];
        cout << setprecision(2) << std::fixed;
        cout << sum / K << " ";
    }
 
    // Compute MA from index K
    float avg;
    for (i = K; i < N; i++) {
        sum -= arr[i - K];
        sum += arr[i];
        avg = sum / K;
        cout << setprecision(2) << std::fixed;
        cout << avg << " ";
    }
}
 
// Driver code
int main()
{
    int arr[] = { 1, 3, 5, 6, 8 };
    int N = sizeof(arr) / sizeof(arr[0]);
    int K = 3;
    ComputeMovingAverage(arr, N, K);
    return 0;
}

Java

// Java code to find the simple moving average
import java.util.*;
class GFG{
 
  // Function to compute moving average
  // of previous K elements
  static void ComputeMovingAverage(int arr[], int N,
                                   int K)
  {
    int i;
    float sum = 0;
 
    // Initial sum of K elements.
    for (i = 0; i < K; i++) {
      sum += arr[i];
      System.out.printf("%.2f ",sum / K);
    }
 
    // Compute MA from index K
    for (i = K; i < N; i++) {
      sum -= arr[i - K];
      sum += arr[i];
      System.out.printf("%.2f ",sum / K);
    }
  }
 
  // Driver code
  public static void main(String[] args)
  {
    int arr[] = { 1, 3, 5, 6, 8 };
    int N = arr.length;
    int K = 3;
    ComputeMovingAverage(arr, N, K);
  }
}
 
// This code is contributed by Rajput-Ji

Python3

# Python code for the above approach
 
# Function to compute moving average
# of previous K elements
def ComputeMovingAverage(arr, N, K):
    i = None
    sum = 0
 
    # Initial sum of K elements.
    for i in range(K):
        sum += arr[i]
        print("%.2f"%(sum / K), end= " ")
 
    # Compute MA from index K
    for i in range(K, N):
        sum -= arr[i - K]
        sum += arr[i]
        avg = sum / K
        print("%.2f"%(avg), end =" ")
 
# Driver code
arr = [1, 3, 5, 6, 8]
N = len(arr)
K = 3
ComputeMovingAverage(arr, N, K)
 
# This code is contributed by Saurabh Jaiswal

C#

// C# code to find the simple moving average
using System;
 
class GFG {
 
  // Function to compute moving average
  // of previous K elements
  static void ComputeMovingAverage(int[] arr, int N,
                                   int K)
  {
    int i;
    float sum = 0;
 
    // Initial sum of K elements.
    for (i = 0; i < K; i++) {
      sum += arr[i];
      Console.Write(Math.Round((sum / K),2) + " ");
    }
 
    // Compute MA from index K
    for (i = K; i < N; i++) {
      sum -= arr[i - K];
      sum += arr[i];
      Console.Write(Math.Round(sum / K, 2) + " ");
    }
  }
 
  // Driver code
  public static void Main(string[] args)
  {
    int[] arr = { 1, 3, 5, 6, 8 };
    int N = arr.Length;
    int K = 3;
    ComputeMovingAverage(arr, N, K);
  }
}
 
// This code is contributed by ukasp.

Javascript

       // JavaScript code for the above approach
 
 
       // Function to compute moving average
       // of previous K elements
       function ComputeMovingAverage(arr, N,
           K) {
           let i;
           let sum = 0;
 
           // Initial sum of K elements.
           for (i = 0; i < K; i++) {
               sum += arr[i];
               document.write((sum / K).toFixed(2) + " ");
           }
 
           // Compute MA from index K
           for (i = K; i < N; i++) {
               sum -= arr[i - K];
               sum += arr[i];
               avg = sum / K;
               document.write((avg).toFixed(2) + " ");
           }
       }
 
       // Driver code
 
       let arr = [1, 3, 5, 6, 8];
       let N = arr.length;
       let K = 3;
       ComputeMovingAverage(arr, N, K);
 
 // This code is contributed by Potta Lokesh
   

输出

0.33 1.33 3.00 4.67 6.33 

时间复杂度： O(N)
空间复杂度： O(1)