如何使用渐进索引从矩阵中捕获值？

Let say I have this Matrix:

假设我有这个矩阵：

public static List<List<string>> WallPattern1550 = new List<List<string>>
{ 
    new List<string> { "3", "2", "1", "1", "2" },
    new List<string> { "1", "2", "2" },
    new List<string> { "2", "1", "2" },
    new List<string> { "2", "2", "1" },
    new List<string> { "2", "1", "1", "1" },
    new List<string> { "1", "2", "1", "1" },
    new List<string> { "1", "1", "2", "1" },
    new List<string> { "1", "1", "1", "2" }
};
publi