Find the number of integers from 1 to n which contains digits 0 ' s ▁ and ▁ 1' s only | Java program to find the number of integers from 1 to n which contains digits 0 ' s ▁ and ▁ 1' s only ; Function to find the number of integers from 1 to n which contains 0 ' s ▁ and ▁ 1' s only ; If number is greater than n ; otherwise add count this number and call two functions ; Driver code
class GFG { static int countNumbers ( int x , int n ) { if ( x > n ) return 0 ; return 1 + countNumbers ( x * 10 , n ) + countNumbers ( x * 10 + 1 , n ) ; } public static void main ( String [ ] args ) { int n = 120 ; System . out . println ( countNumbers ( 1 , n ) ) ; } }