Problem statement

Bioinformatics applications process massive strings of genomic data where memory efficiency is critical. You must locate a specific genetic marker within a large DNA sequence, extract the subsequent 10 characters as the target gene, and format a final report.

Task requirements

• Accept a full DNA string and a target marker string.

• Find the exact starting index of the target marker.

• Extract exactly 10 characters immediately following the marker.

• Generate and return a report string formatted exactly as: "Analysis Complete. Target Sequence: [Sequence]".

• Return "Incomplete target sequence" if there are fewer than 10 characters after the marker.

• Return "Marker not found" if the sequence does not contain the target.

Constraints

• Convert the input string to a ReadOnlySpan<char> using AsSpan() to avoid initial memory allocations.

• Use the IndexOf() method on the span to locate the marker.

• Use the Slice() method to extract the target sequence.

• Use a StringBuilder to construct the final output string.

Good luck trying the exercise! If you’re unsure how to proceed, check the “Solution” tab above.

Get hints

• You need to convert both the full sequence and the marker into spans to use the span-based IndexOf method.

• The starting index of your slice is the found index of the marker plus the length of the marker itself.

• Compare the required target slice length (10 characters) against the remaining length of the span before calling Slice() to prevent runtime out-of-bounds errors.

• Modern .NET allows you to pass a ReadOnlySpan<char> directly into the StringBuilder.Append() method.