Question

How to check if an array contains a pair of numbers whose product is odd in Java

Answer 1

// A product of a pair of integers will always be odd if at least 2 of them are odd

class Program {
    public static boolean arrayContainsAPairOfOddProduct(int[] arr) {
        int sumOdds = 0;
        int numberOfOdds = 2;
    
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] % 2 != 0) {
                if (sumOdds == numberOfOdds) {
                    return true;
                }
                sumOdds++;
            }
        }
        
        if (sumOdds == numberOfOdds) { // for the last array element
            return true;
        }
    
        return false;
    }
    
    public static void main(String[] args) {
        int arr[] = new int[] {2, 2, 4, 4, 6, 6, 7, 10, 10, 9}; // 7 * 9 = 63 -> Odd
        
        System.out.println(arrayContainsAPairOfOddProduct(arr));
    }
}



/*
run:

true

*/

 

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Answer 2

class Program {
    public static boolean arrayContainsAPairOfOddProduct(int[] arr) {
        int oddCount = 0;

        for (int i = 0; i < arr.length; i++) {
            if (arr[i] % 2 != 0) {
                oddCount++; 
                if (oddCount == 2) {
                    break;
                }
            }
        }
        
        return oddCount > 1;
    }
    
    public static void main(String[] args) {
        int arr[] = new int[] {2, 2, 4, 4, 6, 6, 7, 10, 10, 9}; // 7 * 9 = 63 -> Odd
        
        System.out.println(arrayContainsAPairOfOddProduct(arr));
    }
}



/*
run:

true

*/

 

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