Given an integer N, the task is to count the number of binary strings of length N having only 0’s and 1’s.
Note: Since the count can be very large, return the answer modulo 10^9+7.
Explantion: The numbers are 00, 01, 11, 10. Hence the count is 4.
Explantion: The numbers are 000, 001, 011, 010, 111, 101, 110, 100. Hence the count is 8.
Approach: The problem can be easily solved by using Permutation and Combination. At each position of the string there can only be two possibilities, i.e., 0 or 1. Therefore, the total number of permutation of 0 and 1 in a string of length N is given by 2*2*2*…(N times), i.e., 2^N. The answer can be very large, hence modulo by 10^9+7 is returned.
Below is the implementation of the above approach:
- Count number of binary strings such that there is no substring of length greater than or equal to 3 with all 1's
- Generate all binary strings of length n with sub-string "01" appearing exactly twice
- Count binary strings with twice zeros in first half
- Number of strings of length N with no palindromic sub string
- Count number of distinct substrings of a given length
- Count the number of subsequences of length k having equal LCM and HCF
- Number of Binary Trees for given Preorder Sequence length
- Count number of strings (made of R, G and B) using given combination
- Count number of trailing zeros in Binary representation of a number using Bitset
- All possible strings of any length that can be formed from a given string
- Print all possible strings of length k that can be formed from a set of n characters
- Count unique subsequences of length K
- Count of integers of length N and value less than K such that they contain digits only from the given set
- Check if a binary string contains all permutations of length k
- Program to add two binary strings
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