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  • codeforces-200B

    B. Drinks
    time limit per test
    2 seconds
    memory limit per test
    256 megabytes
    input
    standard input
    output
    standard output

    Little Vasya loves orange juice very much. That's why any food and drink in his kitchen necessarily contains orange juice. There are ndrinks in his fridge, the volume fraction of orange juice in the i-th drink equals pi percent.

    One day Vasya decided to make himself an orange cocktail. He took equal proportions of each of the n drinks and mixed them. Then he wondered, how much orange juice the cocktail has.

    Find the volume fraction of orange juice in the final drink.

    Input

    The first input line contains a single integer n (1 ≤ n ≤ 100) — the number of orange-containing drinks in Vasya's fridge. The second line contains n integers pi (0 ≤ pi ≤ 100) — the volume fraction of orange juice in the i-th drink, in percent. The numbers are separated by a space.

    Output

    Print the volume fraction in percent of orange juice in Vasya's cocktail. The answer will be considered correct if the absolute or relative error does not exceed 10  - 4.

    Examples
    input
    3
    50 50 100
    output
    66.666666666667
    input
    4
    0 25 50 75
    output
    37.500000000000
    Note

    Note to the first sample: let's assume that Vasya takes x milliliters of each drink from the fridge. Then the volume of pure juice in the cocktail will equal  milliliters. The total cocktail's volume equals x milliliters, so the volume fraction of the juice in the cocktail equals , that is, 66.(6) percent.

     本题是求平均数的一道题,要求输出小数点后12位。

    #include<iostream>
    #include<iomanip>
    using namespace std;
    int main()
    {
        int n, x;
        double avea, sum = 0;
        cin >> n;
        for (int i = 0;i < n;i++)
        {
            cin >> x;
            sum += x;
        }
        avea =  sum / n;
        cout << fixed << setprecision(12) << avea << endl;
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/chenruijiang/p/7874789.html
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