Last Updated : 23 Jul, 2025
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 : 792Python3
# 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 problemfor more details!
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