Find if it is possible to choose subarray that it contains exactly K even integers

Given 2 positive integers N and K and an array arr[], the task is to find whether it is possible to choose a non-empty subarray of the array such that the subarray contains exactly K even integers.

Examples:

Input: N = 4, K = 2, arr[] = {1, 2, 4, 5}
Output: Yes
Explanation:
We can select the subarray {2, 4} which contains exactly K = 2 even numbers.

Input: N = 3, K = 3, arr[] = {2, 4, 5}
Output: No
Explanation:
There are only two even numbers. Therefore, we cannot choose a subarray with K = 3 even numbers.

Approach: The idea is to count the number of even numbers in the array. Now there can be 3 cases:



  • If the count of even numbers in the array is 0 (i.e.) there are only odd numbers in the array, then we can’t select any subarray
  • If the count of even numbers in the array is ≥ K, then we can easily select a subarray with exactly K even integers
  • Else it is not possible to select a subarray with exactly K even integers

Below is the implementation of the above approach:

CPP

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// C++ program to check if it is possible to
// choose a subarray that contains exactly
// K even integers
#include <bits/stdc++.h>
using namespace std;
  
// Function to check if it is possible to
// choose a subarray that contains exactly
// K even integers
void isPossible(int A[], int n, int k)
{
    // Variable to store the count of
    // even numbers
    int countOfTwo = 0;
    for (int i = 0; i < n; i++) {
        if (A[i] % 2 == 0) {
            countOfTwo++;
        }
    }
  
    // If we have to select 0 even numbers
    // but there is all odd numbers in the array
    if (k == 0 && countOfTwo == n)
        cout << "NO\n";
  
    // If the count of even numbers is greater than
    // or equal to K then we can select a
    // subarray with exactly K even integers
    else if (countOfTwo >= k) {
        cout << "Yes\n";
    }
  
    // If the count of even numbers is less than K
    // then we cannot select any subarray with
    // exactly K even integers
    else
        cout << "No\n";
}
  
// Driver code
int main()
{
    int arr[] = { 1, 2, 4, 5 };
    int K = 2;
    int N = sizeof(arr) / sizeof(arr[0]);
  
    isPossible(arr, N, K);
    return 0;
}

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Java

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// Java program to check if it is possible to
// choose a subarray that contains exactly
// K even integers
import java.util.*;
   
class GFG{
// Function to check if it is possible to
// choose a subarray that contains exactly
// K even integers
static void isPossible(int []A, int n, int k)
{
    // Variable to store the count of
    // even numbers
    int countOfTwo = 0;
    for (int i = 0; i < n; i++) {
        if (A[i] % 2 == 0) {
            countOfTwo++;
        }
    }
  
    // If we have to select 0 even numbers
    // but there is all odd numbers in the array
    if (k == 0 && countOfTwo == n)
        System.out.print("NO");
  
    // If the count of even numbers is greater than
    // or equal to K then we can select a
    // subarray with exactly K even integers
    else if (countOfTwo >= k) {
        System.out.print("YES");
    }
  
    // If the count of even numbers is less than K
    // then we cannot select any subarray with
    // exactly K even integers
    else
        System.out.print("No");
}
  
// Driver Code
public static void main(String[] args)
{
    int []arr = { 1, 2, 4, 5 };
    int K = 2;
    int n = arr.length;
  
    isPossible(arr, n, K);
}
}
  
// This code is contributed by shivanisinghss2110

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Python3

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# Python3 program to check if it is possible to
# choose a subarray that contains exactly
# K even integers
  
# Function to check if it is possible to
# choose a subarray that contains exactly
# K even integers
def isPossible(A, n, k):
      
    # Variable to store the count of
    # even numbers
    countOfTwo = 0
    for i in range(n):
        if (A[i] % 2 == 0):
            countOfTwo += 1
  
    # If we have to select 0 even numbers
    # but there is all odd numbers in the array
    if (k == 0 and countOfTwo == n):
        print("NO\n")
  
    # If the count of even numbers is greater than
    # or equal to K then we can select a
    # subarray with exactly K even integers
    elif (countOfTwo >= k):
        print("Yes\n")
  
    # If the count of even numbers is less than K
    # then we cannot select any subarray with
    # exactly K even integers
    else:
        print("No\n")
  
# Driver code
if __name__ == '__main__':
    arr=[1, 2, 4, 5]
    K = 2
    N = len(arr)
  
    isPossible(arr, N, K)
  
# This code is contributed by mohit kumar 29

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C#

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// C# program to check if it is possible to
// choose a subarray that contains exactly
// K even integers
using System;
  
class GFG{
  
// Function to check if it is possible to
// choose a subarray that contains exactly
// K even integers
static void isPossible(int []A, int n, int k)
{
    // Variable to store the count of
    // even numbers
    int countOfTwo = 0;
    for (int i = 0; i < n; i++) {
        if (A[i] % 2 == 0) {
            countOfTwo++;
        }
    }
  
    // If we have to select 0 even numbers
    // but there is all odd numbers in the array
    if (k == 0 && countOfTwo == n)
        Console.Write("NO");
  
    // If the count of even numbers is greater than
    // or equal to K then we can select a
    // subarray with exactly K even integers
    else if (countOfTwo >= k) {
        Console.Write("Yes");
    }
  
    // If the count of even numbers is less than K
    // then we cannot select any subarray with
    // exactly K even integers
    else
        Console.Write("No");
}
  
// Driver Code
public static void Main()
{
    int []arr = { 1, 2, 4, 5 };
    int K = 2;
    int n = arr.Length;
  
    isPossible(arr, n, K);
}
}
  
// This code is contributed by AbhiThakur

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Output:

Yes

Time Complexity: O(N)

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