语言求以下三数的和,保留2位小数 1~a之和 1~b的平方和 1~c的倒数和

* 语言求和问题
* 数学运算
* a~1和的计算
* b~1平方和的计算
* c~1倒数和的计算
* 保留2位小数
* 舍入规则
* Python: `round()`
* C/C++: `std::fixed` + `std::setprecision(2)`
* 示例代码
* Python:

            total = round(sum(range(1, a+1)), 2)
            square_sum = round(sum(i**2 for i in range(1, b+1)), 2)
            reciprocal_sum = round(sum(1/i for i in range(1, c+1)), 2)

* C++:

            double sum_a = std::round(std::accumulate(1, a+1, 0.0) * 100) / 100;
            double sum_squares = std::round(std::accumulate(1, b+1, 0.0, [](double acc, int i){ return acc + i*i; }) * 100) / 100;
            double sum_reciprocals = std::round(std::accumulate(1, c+1, 0.0, [](double acc, int i){ return acc + 1/i; }) * 100) / 100;