×

Suggest a Topic

Select a Category

Python Program to Count number of binary strings without consecutive 1’s

Given a positive integer N, count all possible distinct binary strings of length N such that there are no consecutive 1’s.

Examples:

Input:  N = 2
Output: 3
// The 3 strings are 00, 01, 10

Input: N = 3
Output: 5
// The 5 strings are 000, 001, 010, 100, 101

Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

Python3

# Python program to count 
# all distinct binary strings 
# without two consecutive 1's 
  
def countStrings(n): 
  
    a =[0 for i in range(n)] 
    b =[0 for i in range(n)] 
    a[0] = b[0] = 1
    for i in range(1, n): 
        a[i] = a[i-1] + b[i-1] 
        b[i] = a[i-1] 
      
    return a[n-1] + b[n-1] 
  
# Driver program to test 
# above functions 
  
print(countStrings(3)) 
  
# This code is contributed 
# by Anant Agarwal. 

Output:

Please refer complete article on Count number of binary strings without consecutive 1’s for more details!

My Personal Notes

Recommended Posts:

Writing code in comment? Please use ide.geeksforgeeks.org, generate link and share the link here.

✍
Write a Testimonial