There are 12 intermediate stations between two places A and B. Find the number of ways in which a train can be made to stop at 4 of these intermediate stations so that no two stopping stations are consecutive?
Examples –
Input : n = 12, s = 4 Output : 126 Input : n = 16, s = 5 Output : 792
# Python code to calculate number # of ways of selecting \'p\' non # consecutive stations out of # \'n\' stations def stopping_station( p, n): num = 1 dem = 1 s = p # selecting \'s\' positions # out of \'n-s+1\' while p ! = 1 : dem * = p p - = 1 t = n - s + 1 while t ! = (n - 2 * s + 1 ): num * = t t - = 1 if (n - s + 1 ) > = s: return int (num / dem) else : # if conditions does not # satisfy of combinatorics return - 1 # driver code num = stopping_station( 4 , 12 ) if num ! = - 1 : print (num) else : print ( "Not Possible" ) # This code is contributed by "Abhishek Sharma 44" |
Output :
126
Please refer complete article on Number of stopping station problem for more details!
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