Count even sum pairs possible by selecting two integers from two given ranges respectively | Java program to implement the above approach ; Function to count maximum even sum pairs in the given range ; Stores the count of even numbers between 1 to X ; Stores the count of odd numbers between 1 to X ; Stores the count of even numbers between 1 to Y ; Stores the count of odd numbers between 1 to Y ; Stores the count of pairs having even sum ; Retuens the count of pairs having even sum ; Driver Code
import java . io . * ; class GFG { static long cntEvenSumPairs ( long X , long Y ) { long cntXEvenNums = X / 2 ; long cntXOddNums = ( X + 1 ) / 2 ; long cntYEvenNums = Y / 2 ; long cntYOddNums = ( Y + 1 ) / 2 ; long cntPairs = ( cntXEvenNums * cntYEvenNums ) + ( cntXOddNums * cntYOddNums ) ; return cntPairs ; } public static void main ( String [ ] args ) { long X = 2 ; long Y = 3 ; System . out . println ( cntEvenSumPairs ( X , Y ) ) ; } }