#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

void findMatchedGenome(string genome1,string genome2,string genome3,string seq);
int main(void) {
   //Declaring variables
findMatchedGenome("TTC","GCC","TCT","");
   return 0;
}
void findMatchedGenome(string genome1,string genome2,string genome3,string seq)
{
   if(genome1.compare("")==0 || genome2.compare("")==0||genome3.compare("")==0|| seq.compare("")==0)
   {
       cout<<"Genomes or sequence is empty."<<endl;
   }
   else if(genome1.length()!=genome2.length() ||
   genome2.length()!=genome3.length() ||
           genome3.length()!=genome1.length())
           {
               cout<<"Lengths of genomes are different."<<endl;
           }
           else
           {
               if(genome1.compare(seq)==0)
               {
                   cout<<"Genome1 is matched to sequence."<<endl;
               }
               else if(genome2.compare(seq)==0)
               {
                   cout<<"Genome2 is matched to sequence."<<endl;
               }
               else if(genome3.compare(seq)==0)
               {
                   cout<<"Genome3 is matched to sequence."<<endl;
               }
               else
               {
                   cout<<"No Genome is matched to sequence."<<endl;
               }

           }
}

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Output:
https://media.cheggcdn.com/media/3af/3af724e3-f6a0-4c87-9f7b-3c62fd4c6f86/phpJeNJal.png