新答案

您可以找到行和列使用以下公式：

You can find the row and column using the following formulas:

int row = floor(-0.5 + sqrt(0.25 + 2 * index));
int triangularNumber = row * (row + 1) / 2;
int column = index - triangularNumber;

之所以有用，是因为每一行的第一项是三角数（0、1、3、6、10、15 ...）。因此，低于 index 的最大三角数为我们提供了 row 行。那么列就是索引与该三角形之间的差。

This works because the first item in each row is a triangular number (0, 1, 3, 6, 10, 15, ...). So the biggest triangular number that is lower than index gives us the row. Then column is simply the difference between index and that triangular number.

此外，请注意，您不需要参数 M 。

Also, note that you don't need the parameter M.

旧答案

此代码将为您提供行和索引的列。

This code will give you both the row and column of index.

int triangularNumber = 0;
int row = 0;
while (triangularNumber + row < index) {
    row ++;
    triangularNumber += row;
}
int column = index - triangularNumber;