Data update

Task/Combinations/DuckDB/combinations.duckdb

@@ -0,0 +1,22 @@
+CREATE OR REPLACE FUNCTION combinations(n, k) as table (
+  WITH RECURSIVE cte(current, remaining) AS (
+    -- start with empty combination and the full list
+    SELECT
+      [],
+      range(1, n + 1)
+    UNION ALL
+    -- recursive case: add one item to the current combination
+    SELECT
+      current || remaining[j:j],
+      remaining[j+1:]
+    FROM cte, range(1, length(remaining)+1) _(j)
+    WHERE length(current) < k
+  )
+  SELECT current AS combination
+  FROM cte
+  WHERE length(current) = k
+);
+
+## Example:
+FROM combinations(5,3)
+ORDER BY combination;