mediumStringsPattern: Mixed
Consecutive Nucleotide Count Solution
Problem Statement
Given a string of nucleotide bases consisting of characters 'A', 'C', 'G', and 'T', write a function to count the number of substrings where no two consecutive characters are the same.
Examples
Example 1:
Input:{"sequence":"ACGT"}
Output:4
Explanation: The substrings with no two consecutive characters representing the same nucleotide base are: A, C, G, T
Example 2:
Input:{"sequence":"AAAA"}
Output:4
Explanation: The substrings with no two consecutive characters representing the same nucleotide base are: A (at each position)
Example 3:
Input:{"sequence":"ATCGATCG"}
Output:16
Explanation: Counting all substrings with no consecutive repeats
Constraints
- 1 <= length of DNA sequence <= 1000
- DNA sequence only contains the characters 'A', 'C', 'G', 'T'
Time: O(n²) Space: O(1)
A more efficient approach uses a sliding window to generate substrings and checks for alternating nucleotide bases. This approach still has a time complexity of O(n²) in the worst case but with a lower constant factor, making it more efficient in practice.
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