結果

問題 No.3072 Speedrun Query
ユーザー qwewe
提出日時 2025-05-14 13:08:09
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 3,263 bytes
コンパイル時間 1,204 ms
コンパイル使用メモリ 90,036 KB
実行使用メモリ 7,848 KB
最終ジャッジ日時 2025-05-14 13:09:50
合計ジャッジ時間 13,744 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge3
このコードへのチャレンジ
（要ログイン）
ファイルパターン 結果
sample WA * 1
other WA * 21
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <iostream> 
#include <cmath>       // Required for sqrtl function (square root for long double)
#include <iomanip>     // Required for std::fixed and std::setprecision for output formatting

int main() {
    // Set up fast input/output.
    // std::ios_base::sync_with_stdio(false) disables synchronization with C standard streams,
    // which can speed up C++ stream operations.
    // std::cin.tie(nullptr) unties cin from cout, further speeding up input operations
    // by not forcing a flush of cout before cin operations.
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int N; // Declare an integer variable N to store the number of elements in the sequence.
    std::cin >> N; // Read the value of N from standard input.

    // Declare a variable 'current_sum' of type long double to store the cumulative sum.
    // long double is used because it typically offers higher precision than double,
    // which is important given the strict error tolerance requirement (10^-15).
    // Initialize the sum to 0.0. The 'L' suffix denotes a long double literal.
    long double current_sum = 0.0L; 

    // Configure the standard output stream (std::cout) for printing floating-point numbers:
    // - std::fixed forces the output to use fixed-point notation (e.g., 123.45)
    //   instead of scientific notation (e.g., 1.2345e+2).
    // - std::setprecision(17) sets the number of digits to display after the decimal point to 17.
    //   This level of precision is chosen to meet the problem's requirement for an absolute
    //   or relative error less than 10^-15. Displaying around 17 decimal digits is generally
    //   sufficient to represent the precision of long double and satisfy the error bounds.
    std::cout << std::fixed << std::setprecision(17); 

    // Loop N times. The loop variable 'i' goes from 0 to N-1.
    // In each iteration, we process the (i+1)-th element of the sequence.
    for (int i = 0; i < N; ++i) {
        long long x; // Declare a variable 'x' of type long long to store the current element.
                     // long long is used because the input values x_i can be up to 10^18,
                     // which fits within a 64-bit signed integer type.
        std::cin >> x; // Read the value of the current element x_i from standard input.
        
        // Calculate the square root of x and add it to the running sum 'current_sum'.
        // - We use the sqrtl function from <cmath>, which computes the square root for long double arguments.
        // - We explicitly cast 'x' to long double using static_cast<long double>(x) before passing it to sqrtl.
        //   This ensures that the calculation uses long double precision.
        // The result is added to 'current_sum'.
        current_sum += sqrtl(static_cast<long double>(x)); 
        
        // Print the current value of the cumulative sum S_k = sum_{j=1}^{i+1} sqrt(x_j).
        // The value is printed according to the formatting set earlier (fixed-point, 17 decimal places).
        // '\n' adds a newline character, so each sum S_k appears on its own line as required.
        std::cout << current_sum << '\n';
    }

    // Return 0 to indicate that the program executed successfully.
    return 0; 
}
0