1104 Sum of Number Segments

	#include<iostream>
	using namespace std;
	int main()
	{
		#ifndef ONLINE_JUDGE
		freopen("in.txt","r",stdin);
		#endif
		int n;
		cin>>n;
		double b[100001];
		double ans=0.0;
		for(int i=1;i<=n;i++){
			cin>>b[i];
			ans=ans+i*(n-i+1)*b[i];
		}
		printf("%.2f",ans);
		return 0;
		
	}

#include<iostream>
using namespace std;
int main() {
	#ifndef ONLINE_JUDGE
	freopen("in.txt","r",stdin);
	#endif
    int n;
    cin >> n;
    double a[100001];
    double sum = 0.0;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        sum = sum + a[i] * i * (n - i + 1);
    }
    printf("%.2f", sum);
    return 0;
}

double*int和int*double结果不一样！！！第一段15分，第二段代码20分，就是顺序不一样，唉~玄学