编写一个函数来计算C中一行的范围内的平方和 [英] Writing a function that calculates the sum of squares within a range in one line in C

问题描述

我的尝试

double sum_squares_from(double x, double n){

    return n<=0 ? 0 : x*x + sum_squares_from((x+n-1)*(x+n-1),n-1);

}

我的教授不是使用循环，而是希望我们编写这样的函数... 练习要求的是一个函数sum_squares_from()，其中double x是起始数字，n是数字.例如，如果执行x = 2和n = 4，则得到2 * 2 + 3 * 3 + 4 * 4 + 5 * 5.如果n == 0，则返回零.

Instead of using loops my professor wants us to write functions like this... What the exercise asks for is a function sum_squares_from() with double x being the starting number and n is the number of number. For example if you do x = 2 and n = 4 you get 2*2+3*3+4*4+5*5. It returns zero if n == 0.

我的想法是，在我的示例中，我所拥有的基本上是x * x +(x + 1)(x + 1)+(x + 1 + 1)(x + 1 + 1)+(x + 1 + 1 +1)(x + 1 + 1 + 1)=(x + 0)(x + 0)+(x + 1)(x + 1)+(x + 2)(x + 2)+(x + 3 )(x + 3)=(x + n-1)^ 2重复n次，其中n每次递减1直到它变为零，然后将所有内容相加.

My thinking was that in my example what I have is basically x*x+(x+1)(x+1)+(x+1+1)(x+1+1)+(x+1+1+1)(x+1+1+1) = (x+0)(x+0)+(x+1)(x+1)+(x+2)(x+2)+(x+3)(x+3) = (x+n-1)^2 repeated n times where n gets decremented every time by one until it becomes zero and then you sum everything.

我做对了吗?

(如果我的教授似乎有点苛求...他不知不觉地以某种方式在脑海中做了这种事情.可怕的家伙)

(if my professor seems a bit demanding... he somehow does this sort of thing all in his head without auxiliary calculations. Scary guy)

推荐答案

也许是吗?

double sum_squares_from(double x, double n) {
    return n <= 0 ? 0 : (x + n - 1) * (x + n - 1) + sum_squares_from(x, n - 1);
}

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