求期望方差

#include<iostream>
#include<cmath>
using namespace std;
int main()
{
    double a[100], sum = 0, expect = 0, variance = 0;
    int n;
    scanf("%d",&n);
    for(int i = 0; i < n; i++)
    {
        scanf("%lf",&a[i]);
        sum+=a[i];
    }
    expect = sum / n;
    for(i = 0; i < n; i++)
    {
        variance += pow((a[i]- expect),2);
    }
    variance = variance / (n-1);
    cout<<"期望:"<<expect<<endl;
    cout<<"方差:"<<variance<<endl;
    return 0;
}