Count number of even and odd elements in an array - GeeksforGeeks

05 Mar, 2021
For the given array of integers, count even and odd elements.
Examples: 
Input: 
int arr[5] = {2, 3, 4, 5, 6}
Output: 
Number of even elements = 3    
Number of odd elements = 2  

Input:
int arr[5] = {22, 32, 42, 52, 62}
Output: 
Number of even elements = 5  
Number of odd elements = 0
Solution: We can also check if a number is odd or even
By doing AND of 1 and that digit, if the result comes out to be 1 then the number is odd otherwise even.
By its divisibility by 2. A number is said to be odd if it is not divisible by 2, otherwise its even. 
Here, we will check if a number is odd, then we will increment the odd counter otherwise we will increment the even counter. 
Below is the implementation of the above approach:
C++
Java
Python3
C#
PHP
Javascript
// CPP program to count number of even// and odd elements in an array#include <iostream>using namespace std; void CountingEvenOdd(int arr[], int arr_size){    int even_count = 0;    int odd_count = 0;     // loop to read all the values in the array    for (int i = 0; i < arr_size; i++) {                   // checking if a number is completely        // divisible by 2        if (arr[i] & 1 == 1)            odd_count++;        else            even_count++;    }     cout << "Number of even elements = " << even_count         << "\nNumber of odd elements = " << odd_count;} // Driver Codeint main(){    int arr[] = { 2, 3, 4, 5, 6 };    int n = sizeof(arr) / sizeof(arr[0]);             // Function Call    CountingEvenOdd(arr, n);}
// JAVA program to count number of even// and odd elements in an arrayimport java.io.*; class GFG {     static void CountingEvenOdd(int arr[], int arr_size)    {        int even_count = 0;        int odd_count = 0;         // loop to read all the values in        // the array        for (int i = 0; i < arr_size; i++) {                           // checking if a number is            // completely divisible by 2            if ((arr[i] & 1) == 1)                odd_count++;            else                even_count++;        }         System.out.println("Number of even"                           + " elements = " + even_count                           + " Number of odd elements = "                           + odd_count);    }     // Driver Code    public static void main(String[] args)    {        int arr[] = { 2, 3, 4, 5, 6 };        int n = arr.length;                     // Function Call        CountingEvenOdd(arr, n);    }} // This code is Contributed by anuj_67.
# Python3 program to count number of# even and odd elements in an array  def CountingEvenOdd(arr, arr_size):    even_count = 0    odd_count = 0     # loop to read all the values    # in the array    for i in range(arr_size):         # checking if a number is        # completely divisible by 2        if (arr[i] & 1 == 1):            odd_count += 1        else:            even_count += 1     print("Number of even elements = ",          even_count)    print("Number of odd elements = ",          odd_count)  # Driver Codearr = [2, 3, 4, 5, 6]n = len(arr) # Function CallCountingEvenOdd(arr, n) # This code is contributed by sahishelangia
// C# program to count number of even// and odd elements in an arrayusing System; class GFG {     static void CountingEvenOdd(int[] arr, int arr_size)    {        int even_count = 0;        int odd_count = 0;         // loop to read all the values in        // the array        for (int i = 0; i < arr_size; i++) {                           // checking if a number is            // completely divisible by 2            if ((arr[i] & 1) == 1)                odd_count++;            else                even_count++;        }         Console.WriteLine("Number of even"                          + " elements = " + even_count                          + " Number of odd elements = "                          + odd_count);    }     // Driver Code    public static void Main()    {        int[] arr = { 2, 3, 4, 5, 6 };        int n = arr.Length;                 // Function Call        CountingEvenOdd(arr, n);    }} // This code is Contributed by anuj_67.
<?php// PHP program to count number of even// and odd elements in an array function CountingEvenOdd( $arr, $arr_size){    $even_count = 0;            $odd_count = 0;                         // loop to read all the values in    // the array    for( $i = 0 ; $i < $arr_size ; $i++)    {        // checking if a number is        // completely divisible by 2        if ($arr[$i] & 1 == 1)            $odd_count ++ ;            else                           $even_count ++ ;            }     echo "Number of even elements = " ,        $even_count," Number of odd " ,            "elements = " ,$odd_count ;    } // Driver Code    $arr = array(2, 3, 4, 5, 6);    $n = count($arr);     // Function Call    CountingEvenOdd($arr, $n); // This code is Contributed by anuj_67.?>
<script> // Javascript program to count number of even// and odd elements in an array function CountingEvenOdd(arr, arr_size){    let even_count = 0;    let odd_count = 0;     // loop to read all the values in the array    for (let i = 0; i < arr_size; i++) {                 // checking if a number is completely        // divisible by 2        if (arr[i] & 1 == 1)            odd_count++;        else            even_count++;    }     document.write("Number of even elements = " + even_count        + "<br>" + "Number of odd elements = " + odd_count);} // Driver Code     let arr = [ 2, 3, 4, 5, 6 ];    let n = arr.length;         // Function Call    CountingEvenOdd(arr, n); // This code is contributed by Mayank Tyagi </script>
Number of even elements = 3
Number of odd elements = 2
Time Complexity: O(n)
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