Maximum Average Sub-array of K length in Java

May 2, 2023

Maximum Average Sub-array of K length in Java

On this page we will discuss about Maximum Average sub-array of k length in Java language . We have to Find out the maximum possible average value of sub-array of K length from  given sequence of N integers, a[1], a[2], , , , a[N] of  N length and a integer K integer.
Average sub-array

Maximum Average Sub-array of K length in Java

In Java, maximum average subarray of k length pertains to a contiguous sub-array of length k in a given array of numbers, where the average (mean) of the k elements is the highest among all possible sub-arrays of length k in that array. In simpler words, it refers to the sub-array of k consecutive elements whose sum is the largest possible among all sub-arrays of k consecutive elements in the array, resulting in the highest average value.

For example,consider the array

[1, 12, -5, -6, 50, 3] and k=4.

The subarrays of length 4 are [1, 12, -5, -6], [12, -5, -6, 50], [-5, -6, 50, 3], and their averages are 0.5, 12.75, and 10.5 respectively. The maximum average subarray of length 4 in this case is [12, -5, -6, 50], whose average is 12.75.

Maximum Average Sub-array of K length in Java
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Algorithm:

  1. Initialize max_sum with the sum of the first k elements of arr and max_end with k-1, which represent the sum and ending index of the first subarray of length k.

  2. Loop through the input array arr from index k to n-1 and for each index i, compute the sum of the subarray of length k ending at index i, i.e., curr_sum = sum of elements from arr[i-k+1] to arr[i].

  3. Compare curr_sum with max_sum. If curr_sum is greater than max_sum, update max_sum with curr_sum and update max_end with the current index i.

  4. After the loop, max_end will represent the ending index of the maximum average subarray of length k.

  5. Return the starting index of the maximum average subarray of length k as max_end - k + 1.

Java code for maximum average sub-array of k length

Run 
import java.util.Arrays;

public class Main {
    // 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];
        }

        int max_sum = csum[k - 1], max_end = k - 1;
        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;
            }
        }

        // Return starting index
        return max_end - k + 1;
    }

    // Driver program
    public static void main(String[] args) {
        int[] arr = {-1, 10, -15, -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));
    }
}

Output

The maximum average subarray of length 4 begins at index 1

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Introduction to Trees

Binary Trees

Binary Search Trees

Traversals

  • Traversal in Trees
  • Tree Traversals: Breadth-First Search (BFS) : C | C++ | Java
  • Tree Traversals: Depth First Search (DFS) : C | C++ | Java
  • Construct a Binary Tree from Postorder and Inorder

B – Trees

AVL Trees

  • AVL Trees
    • AVL Trees: Introduction
    • AVL Tree Insertion :  C | C++ | Java
    • AVL Tree Deletion : C | C++ | Java
    • Insertion in a Binary Tree (Level Order) – C | C++ | Java
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    • Searching in a Binary Search Tree – C | C++ | Java

Complete Programs for Trees

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  • Level Order Traversal – C | C++ | Java
  • Construct Tree from given Inorder and Preorder traversals – C | C++ | Java
  • Construct Tree from given Postorder and Inorder traversals – C | C++ | Java
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  • check whether tree is Symmetric  C| C++| Java.
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