题解 | #求1+2+3+...+n#

class A{
    public:
    A(){
    ++N;
    sum+=N;
     }
    static void Reset(){
    N=0;
    sum=0;
    }
    static int N;
    static int sum;
};
int A::N=0;
int A::sum=0;
class Solution {
public:
    int Sum_Solution(int n) {
       A::Reset();
       A *a=new A[n];
        delete []a;
        a=nullptr;
       return A::sum;
    }
};