Gene finding

Recall that in prokaryotic genomes, the sequence coding for a protein occurs as one contiguous open reading frame, and that an open reading frame begins with the start codon ATG (methionine) in most species and ends with a stop codon TAA, TAG, or TGA.

For example, the DNA sequence of Bacteriophage $\phi$ -X174, which was the first genome to be sequenced, has 117 open reading frames (11 of which are protein coding genes) within a circular single strand of 5,386 nucleotides.

Write code for the gene finding problem. The program must implement and use the GENE-FINDING function in the pseudocode discussed in class, which is iterative and is not allowed to perform input/output operations. Make one submission with Python code and another submission with C++ code.

Input

The input is a string $s$ over the alphabet $\Sigma=\{A,C,G,T\}$ .

Output

The output is a minimal substring of $s$ (an open reading frame) from a start codon to a stop codon.

Problem information

Author: Gabriel Valiente

Generation: 2026-01-25T17:35:24.985Z