1104 Sum of Number Segments （20 point(s)）

#include<iostream> #include<cstdio> using namespace std; double res, x; int n; int main() { scanf("%d", &n); for(int i = 1; i <= n; ++i) scanf("%lf", &x), res += x * (n - i + 1) * i; printf("%.2f\n

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