Noob_sol

import java .io.*;

class GFG {

    // Returns beginning index 
    // of maximum average
    // subarray of length 'k'
    static int findMaxAverage(int []arr, 
                           int n, int k)
    {
        
        // Check if 'k' is valid
        if (k > n)
            return -1;
    
        // Create and fill array 
        // to store cumulative
        // sum. csum[i] stores 
        // sum of arr[0] to arr[i]
        int []csum = new int[n];
        
        csum[0] = arr[0];
        for (int i = 1; i < n; i++)
        csum[i] = csum[i - 1] + arr[i];
    
        // Initialize max_sm as 
        // sum of first subarray
        int max_sum = csum[k - 1], 
                    max_end = k - 1;
    
        // Find sum of other 
        // subarrays and update
        // max_sum if required.
        for (int i = k; i < n; i++)
        {
            int curr_sum = csum[i] - 
                    csum[i - k];
            if (curr_sum > max_sum)
            {
                max_sum = curr_sum;
                max_end = i;
            }
        }
    
        // To avoid memory leak
        //delete [] csum; 
        
        // Return starting index
        return max_end - k + 1;
    }

    // Driver Code
    static public void main (String[] args)
    {
        int []arr = {1, 12, -5, -6, 50, 3};
        int k = 4;
        int n = arr.length;
        
        System.out.println("The maximum "
          + "average subarray of length "
                + k + " begins at index "
            + findMaxAverage(arr, n, k));
    }
}