Question

给定x = 3;

我需要计算x = 3 + 2 + 1

值的总和

x = 6;

int input = 3;
int retVal = 0;

for (int i = 0; i <= input; i++)
{
    retVal += i;            
}
Console.WriteLine(retVal);

我能够计算x的总和。

我如何计算x ^ 2总和的值

例如

x         x^2

1         1 
2         4
3         9

summation of x = 6
summation of x^2 = 14

我尝试过以下代码

int input = 3;
int retVal = 0;
int summation = input * input;
for (int i = 0; i <= input; i++)
{
    retVal += i;
    summation +=  i;
}
Console.WriteLine(retVal);
Console.WriteLine(summation);

Answer 1

让我向您解释一下您的代码：

      int input = 3;
        int retVal = 0;
        int summation = input * input; //summation is equal to 9
        for (int i = 0; i <= input; i++)
        {
            retVal += i; 
            summation +=  i; /*this is basically saying add summation plus i 
                               tosummation (9 is assigned 9 + 0 so summation is still 9). Then, when i is 1, 
                               summation changes to 10. When i is 2, summation changes to 12, and when i is 3,
                               summation is 15. What you should be doing is initialize summation to 0 and in 
                               the for loop, do this: summation +=  i * i (summation is assigned summation + (i * i)) Also, no need to start i from 0 (it is doing one extra loop for nothing). You should start i from 1. */
        }
        Console.WriteLine(retVal);
        Console.WriteLine(summation); //Another user already provided the solution. I just wanted to explain you your code.

Answer 2

您可以使用Enumerable.Range()来实现此目的。

public static int Summation(int count, Func<int, int> series)
{
    return Enumerable.Range(1, count).Select(series).Sum();
}

使用示例 - Summation(3, x => x * x)将返回14。

计算X ^ 2的总和

2 个答案: