QAQ
struct Person
{
    int id,sum,a,b,c;
    bool operator < (const Person &t) const
    {
        if(sum!=t.sum)  return sum>t.sum;//sum由大到小
        if(a!=t.a)      return a>t.a;//a由大到小
        return id<t.id;//id由小到大
    }
}q[N];
sort(q+1,q+n+1);

way2:
struct Person
{
    int id,sum,a,b,c;
}q[N];
bool cmp(Person &a,Person&b)
{
    if(a.sum!=b.sum)  return a.sum>b.sum;//大到小
    if(a.a!=b.a)  return a.a>b.a;//大到小
    return a.id<b.id;//小到大
}
 sort(q+1,q+n+1,cmp);