如何在C#中为嵌套循环编写递归函数

Question

我如何为循环编写递归函数？我正在对这些数组元素求和。

int[,,,] exampleArray = new int[1,2,3,4];
int sum = 0;
for (int i = 0; i < 1; i++)
{
for (int j = 0; j < 2; j++)
{
for (int k = 0; k < 3; k++)
{
for (int l = 0; l < 4; l++)
{
sum += exampleArray[i, j, k, l];
}
}
}
}
Console.WriteLine(sum);

Answer 1

它实际上很简单，只需要一种将所有4个索引表示为单个变量的方法：

static int recursiveSum(int[,,,] a, int index = 0)
{
int ti = index;
int l = ti % a.GetLength(3); ti /= a.GetLength(3);
int k = ti % a.GetLength(2); ti /= a.GetLength(2);
int j = ti % a.GetLength(1); ti /= a.GetLength(1);
int i = ti % a.GetLength(0); ti /= a.GetLength(0);
if (ti > 0) {
return 0;
}
return a[i, j, k, l] + recursiveSum(a, index + 1);
}
static void Main(string[] args)
{
int[,,,] exampleArray = new int[1, 2, 3, 4];
int sum = recursiveSum(exampleArray);
Console.WriteLine(sum);
}