Counting numbers of n digits that are monotone | Java program to count numbers of n digits that are monotone . ; Considering all possible digits as { 1 , 2 , 3 , . .9 } ; DP [ i ] [ j ] is going to store monotone numbers of length i + 1 considering j + 1 digits . ; Unit length numbers ; Single digit numbers ; Filling rest of the entries in bottom up manner . ; Driver code .
class GFG { static final int DP_s = 9 ; static int getNumMonotone ( int len ) { int [ ] [ ] DP = new int [ len ] [ DP_s ] ; for ( int i = 0 ; i < DP_s ; ++ i ) DP [ 0 ] [ i ] = i + 1 ; for ( int i = 0 ; i < len ; ++ i ) DP [ i ] [ 0 ] = 1 ; for ( int i = 1 ; i < len ; ++ i ) for ( int j = 1 ; j < DP_s ; ++ j ) DP [ i ] [ j ] = DP [ i - 1 ] [ j ] + DP [ i ] [ j - 1 ] ; return DP [ len - 1 ] [ DP_s - 1 ] ; } public static void main ( String [ ] args ) { System . out . println ( getNumMonotone ( 10 ) ) ; } }