Count of pairs from 1 to a and 1 to b whose sum is divisible by N | Java implementation of above approach ; Function to find the distinct pairs from 1 - a & 1 - b such that their sum is divisible by n . ; pairs from 1 to n * ( a / n ) and 1 to n * ( b / n ) ; pairs from 1 to n * ( a / n ) and n * ( b / n ) to b ; pairs from n * ( a / n ) to a and 1 to n * ( b / n ) ; pairs from n * ( a / n ) to a and n * ( b / n ) to b ; Return answer ; Driver code
import java . io . * ; class GFG { static int findCountOfPairs ( int a , int b , int n ) { int ans = 0 ; ans += n * ( a / n ) * ( b / n ) ; ans += ( a / n ) * ( b % n ) ; ans += ( a % n ) * ( b / n ) ; ans += ( ( a % n ) + ( b % n ) ) / n ; return ans ; } public static void main ( String [ ] args ) { int a = 5 , b = 13 , n = 3 ; System . out . println ( findCountOfPairs ( a , b , n ) ) ; } }