ACM 2126 Factoring a Polynomial

其实就是实系数多项式分解定理!n>=1的实系数多项式在实数域上都可以分解成一次因式与二次不可约因式的乘积!
在实数域上，奇次一定有一个根，偶次有共轭虚根,总是可以分解成两个n/2的多项式。

#include  < iostream >
#include  < iomanip >
using   namespace  std;

int  main()
{
    int a,b,c,n;
    while(cin>>n)
    {
        if(n<2)    
        {
            while(n>=0)
            {
                n--;
                cin>>a;
            }
            cout<<"YES"<<endl;
        }
        else if(n==2)
        {
            cin>>a>>b>>c;
            if(b*b>=4*a*c)
                cout<<"NO"<<endl;
            else
                cout<<"YES"<<endl;
        }
        else
        {
            while(n>=0)
            {
                n--;
                cin>>a;
            }
            cout<<"NO"<<endl;
        }
    }
    return 0;
}