求助

错误原因似乎是定义数组是只调用了无参构造函数，totalscore只在那时候加了：

不知道怎么解决，求大佬帮助一下

#include<iostream>
using namespace std;
class student{
private:
int id;
string name;
int score;
static int cnt;
static int totalscore;
public:
student(){
cnt++;
totalscore += score;
}
student(int a, string b, int c){
cnt++; this->id = a; this->name = b; this->score = c; totalscore += this->score; }
~student(){
totalscore -= this->score;
cnt--;
}
friend std::istream& operator>>(std::istream &in, student& m){
in >> m.id >> m.name >> m.score;
return in;
}
void show(){
cout << "学生总人数：" << cnt << endl << "平均分：" << totalscore / cnt << endl;
}
};
int student::cnt = 0;
int student::totalscore = 0;
int main(void){
int cnt ;
scanf("%d",&cnt);
student s[cnt];
for(int i=0;i<cnt;i++) { cin>>s[i]; }
student *t = new student(23,"hely",89);
s[0].show();
delete t; s[0].show();
}