DNA （C++代码）

参考代码:

#include <iostream>
using namespace std;
int main()
{
    int n,a,b,flag;
    cin>>n;
    while(n--){
        cin>>a>>b;
        cout<<'X';
        for(int k=1;k<=a-2;k++)
            cout<<" ";
        cout<<'X'<<endl;
        for(int i=1;i<=b;i++) //DNA重复的次数
        {
            for(int j=2;j<=a;j++)
            {
                flag=0;
                int sub=j;
                if(j>a/2+1)sub=a-j+1;
                for(int k=1;k<=sub-1;k++)
                    cout<<" ";
                cout<<'X';
                for(int k=1;k<=a-2*sub;k++){
                        cout<<" ";
                        if(flag==0)flag=1;
                }
                if(flag)cout<<'X'<<endl;
                else cout<<endl;
            }
        }
        cout<<endl;
    }
    return 0;
}