Arrays and Iteration

Find Maximum

Scan the array once, keeping the largest value seen so far. The replay highlights when a candidate replaces the running maximum.

Algorithm

Basic Implementation

basic.sql 
.mode list
.headers off
CREATE TABLE arr(idx INTEGER PRIMARY KEY, val INTEGER);
INSERT INTO arr(idx, val) VALUES
  (0, 3), (1, 1), (2, 4), (3, 1), (4, 5), (5, 9), (6, 2), (7, 6);
WITH RECURSIVE scan(idx, best) AS (
  SELECT 0, (SELECT val FROM arr WHERE idx = 0)
  UNION ALL
  SELECT idx + 1,
         MAX(best, (SELECT val FROM arr WHERE idx = scan.idx + 1))
  FROM scan
  WHERE idx + 1 < (SELECT COUNT(*) FROM arr)
)
SELECT best FROM scan ORDER BY idx DESC LIMIT 1;

Complexity

  • Time: O(n)
  • Space: O(1)

Implementation notes

  • Keep the explicit control flow. Library shortcuts would hide the state changes this lesson is meant to replay.
  • The final output is intentionally small and deterministic for cross-language comparison.
execution replay The checked-in replay follows the language-neutral state table for `array-find-max`.
cross-language comparison This SQL DSA version keeps the same data and final output as every other DSA book in this wave.