text: Count ways to select N pairs of candies of distinct colors ( Dynamic Programming + Bitmasking ) | Java program to implement the above approach ; Function to count ways to select N distinct pairs of candies with different colours ; If n pairs are selected ; Stores count of ways to select the i - th pair ; Iterate over the range [ 0 , n ] ; If pair ( i , j ) is not included ; Driver Code
code: import java . io . * ; import java . lang . * ; import java . util . * ; class GFG { static int numOfWays ( int a [ ] [ ] , int n , int i , HashSet < Integer > blue ) { if ( i == n ) return 1 ; int count = 0 ; for ( int j = 0 ; j < n ; j ++ ) { if ( a [ i ] [ j ] == 1 && ! blue . contains ( j ) ) { blue . add ( j ) ; count += numOfWays ( a , n , i + 1 , blue ) ; blue . remove ( j ) ; } } return count ; } public static void main ( String [ ] args ) { int n = 3 ; int mat [ ] [ ] = { { 0 , 1 , 1 } , { 1 , 0 , 1 } , { 1 , 1 , 1 } } ; HashSet < Integer > mpp = new HashSet < > ( ) ; System . out . println ( ( numOfWays ( mat , n , 0 , mpp ) ) ) ; } }