第五道题answer:
#include <iostream>
#include <string>
using namespace std;
//从2个红球,3个白球,4个黑球中任意取出5个球,
int main()
{
    for( int i=1 ; i<4 ; i++ )
    {
        
        for ( int j=0 ; j+i<6 && j<3 ; j++ )
        {
             cout<<i<<"个白球"<<endl;
             cout<<j<<"个红球"<<endl;
             if ( 5-i-j > 0)
             {
                 cout<<5-i-j<<"个黑球"<<endl;
             }
             else
                cout<<"0个黑球"<<endl;
             cout<<"**
  **"<<endl;
        }
        cout<<"-------- -------"<<endl;
    }
    return 0;
}