Help me in solving DNASTORAGE problem

My issue

My code

#include <iostream>
using namespace std;

int main() {
	int t,n;
	string s[30];
	cin>>t;
	while(t--)
	{
	    cin>>n;
	    cin>>s;
	    int j=0;
	    while(j<n)
	    {
	        if(s[j]==0){
	            if(s[j+1]==0)
	            printf("A");
	            else
	            printf("T");
	        }
	       else if(s[j]==1){
	           if(s[j+1]==0)
	            printf("C");
	            else
	            printf("G");
	       }
	            j+=2;
	    }
	    cout<<endl;
	    
	}
	return 0;
}

Problem Link: DNASTORAGE Problem - CodeChef

My Program gives wrong output when i think its correct and should work properly

One problem is the declaration
string s[30];
where you declare an array of strings instead of just one single string.
Another problem are lines like

if(s[j]==0){

where you compare characters with integers. E.g., correct would be something like

if(s[j]=='0'){

thank you