Add initialize_2d_list snippet

snippets/initialiaze_2d_list.md

@@ -0,0 +1,20 @@
+---
+title: initialize_2d_list
+tags: list,intermediate
+---
+
+Initializes a 2D list of given width and height and value.
+
+Use array comprehension and `range()` to generate `h` rows where each is a list with length `h`, initialized with `val`.
+If `val` is not provided, default to `None`.
+
+Explain briefly how the snippet works.
+
+```py
+def initialize_2d_list(w,h, val = None):
+  return [[val for x in range(w)] for y in range(h)]
+```
+
+```py
+initialize_2d_list(2, 2, 0) # [[0,0], [0,0]]
+```