Initial commit: Days 1 - 5

day04.sql

@@ -0,0 +1,95 @@
+with recursive
+
+raw as (
+    select split(content, e'\n') as content from read_text('data/04.in')
+),
+
+lines as (
+    select
+        string_split(unnest(content), '') as line,
+        generate_subscripts(content, 1) as row
+    from raw
+),
+
+grid as (
+    select
+        unnest(line) as ch,
+        generate_subscripts(line, 1) as col,
+        row
+    from lines
+),
+
+rolls as (
+    select
+        row,
+        col
+    from grid
+    where ch = '@'
+),
+
+accessible as (
+    select
+        pos.row,
+        pos.col
+    from rolls pos, rolls adj
+    where
+        adj.row between pos.row - 1 and pos.row + 1
+        and adj.col between pos.col - 1 and pos.col + 1
+    group by pos.row, pos.col
+    having count(*) < 5
+),
+
+remove (row, col, present, level) as (
+    select
+        row,
+        col,
+        true
+    from rolls
+
+    union all
+
+    select
+        pos.row,
+        pos.col,
+        pos.present and 4 < (
+            select count(*)
+            from remove adj
+            where
+                adj.present
+                and adj.row between pos.row - 1 and pos.row + 1
+                and adj.col between pos.col - 1 and pos.col + 1
+        )
+    from remove pos
+    where
+        exists (
+            select
+                pos.row,
+                pos.col,
+                count(*) as c
+            from remove pos, remove adj
+            where
+                pos.present
+                and adj.present
+                and adj.row between pos.row - 1 and pos.row + 1
+                and adj.col between pos.col - 1 and pos.col + 1
+            group by pos.row, pos.col
+            having c < 5
+        )
+),
+
+removed as (
+    select
+        row,
+        col
+    from remove
+    group by row, col
+    having bool_or(not present)
+),
+
+part2 as (
+    select (select count(*) from removed) as solution
+)
+
+select
+    (select count(*) from accessible) as p1,
+    (select count(*) from removed) as p2;