Given an array, the task is to find the average of that array. Average is the sum of the array elements divided by the number of elements.
Examples:
Input: arr[] = {1, 2, 3, 4, 5}
Output: 3
Sum of the elements is 1+2+3+4+5 = 15
and total number of elements is 5.
So average is 15/5 = 3Input: arr[] = {5, 3, 6, 7, 5, 3}
Output: 4.83333
Sum of the elements is 5+3+6+7+5+3 = 29
and total number of elements is 6.
So average is 29/6 = 4.83333.
1. Iterative Approach
The iterative program is easy. We need to find the sum and divide the sum by the total number of elements.
Approach
- Iterate each element of an array using a loop.
- Sum up each element of the array till we reach the end of the array.
- Divide the sum by the total number of elements and return the average.
Below is the C++ program to find the average of that array using the Iterative approach:
C++
// C++ program to calculate average// of array elements#include <iostream>using namespace std;// Function that return average// of an array.double average(int a[], int n){ // Find sum of array element int sum = 0; for (int i = 0; i < n; i++) sum += a[i]; return (double)sum / n;}// Driver codeint main(){ int arr[] = { 10, 2, 3, 4, 5, 6, 7, 8, 9 }; int n = sizeof(arr) / sizeof(arr[0]); cout << average(arr, n) << endl; return 0;} |
6
The complexity of the method above
Time Complexity: O(n), The time complexity of the above code is O(n) as it loops through all elements of the array to calculate the sum.
Auxiliary Space: O(1), The space complexity is O(1) as no extra space is used.
2. Recursive Approach
The idea is to pass the index of the element as an additional parameter and recursively compute the sum. After computing the sum, divide the sum by n.
Approach
- We will call the function again and again till we reach the end of an array.
- We will sum every element of the array and when we reach the end of an array, we will return the average of the array.
Below is the C++ program to find the average of the array using the Recursive approach:
C++
// C++ program to calculate average// of array elements#include <iostream>using namespace std;// Recursively computes average// of a[]double avgRec(int a[], int i, int n){ // Last element if (i == n - 1) return a[i]; // When index is 0, divide sum // computed so far by n. if (i == 0) return ((a[i] + avgRec(a, i + 1, n)) / n); // Compute sum return (a[i] + avgRec(a, i + 1, n));}// Function that return average// of an array.double average(int a[], int n) { return avgRec(a, 0, n); }// Driver codeint main(){ int arr[] = { 10, 2, 3, 4, 5, 6, 7, 8, 9 }; int n = sizeof(arr) / sizeof(arr[0]); cout << average(arr, n) << endl; return 0;} |
6
The complexity of the above program
Time Complexity: O(n)
Auxiliary Space: O(n)
Related Article: Average of a stream of numbers
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