How to find a sub-list of two consecutive items in a list using Linq

Question

Suppose that we have a list of strings like

\"A\", \"B\", \"C\", \"D\", \"E\", \"F\"

Now I\'d like to search for a sub-list of

Answer 1

I don't think LINQ is appropriate here.

A more efficient solution could be to find "D" then just check it isn't at the end and that "E" is at the next index:

int i = list.FindIndex(x => x == "D");
int p = (i < list.Count - 1) && (list[i + 1] == "E") ? i : -1;

This avoids looping twice to find both indices, and also still matches if "E" appears next to "D" but also before it, e.g. {"E", "C", "D", "E"}