PAT (Advanced Level) 1104. Sum of Number Segments (20)

简单题。

#include<cstdio>

#include<cstring>

#include<cmath>

#include<vector>

#include<map>

#include<queue>

#include<stack>

#include<algorithm>

using namespace std;

int n;

double a[+];

double b[+];

double sum=;

int main()

{

    scanf("%d",&n);

    for(int i=;i<=n;i++) b[i]=1.0*(n-i+)*i;

    for(int i=;i<=n;i++) scanf("%lf",&a[i]);

    for(int i=;i<=n;i++) sum=sum+b[i]*a[i];

    printf("%.2lf\n",sum);

    return ;

}