From 8ab2f8061507be8561b955281dce66561dd00164 Mon Sep 17 00:00:00 2001
From: giles <giles.bradshaw@rose-ash.com>
Date: Mon, 11 May 2026 05:04:37 +0000
Subject: [PATCH] ocaml: phase 5.1 daily_temperatures.ml baseline (sum of waits
 = 10)
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Monotonic decreasing stack — for each day i, pop entries from
the stack whose temperature is strictly less than today's; their
answer is (i - popped_index).

  temps  = [73; 74; 75; 71; 69; 72; 76; 73]
  answer = [ 1;  1;  4;  2;  1;  1;  0;  0]
  sum    = 10

Complementary to next_greater.ml (iter 256) — same monotonic-stack
skeleton but stores the distance to the next greater element
rather than its value.

Tests `match !stack with | top :: rest when …` pattern with
guard inside a while-cont-flag loop.

198 baseline programs total.
---
 lib/ocaml/baseline/daily_temperatures.ml | 24 ++++++++++++++++++++++++
 lib/ocaml/baseline/expected.json         |  1 +
 plans/ocaml-on-sx.md                     | 10 ++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 lib/ocaml/baseline/daily_temperatures.ml

diff --git a/lib/ocaml/baseline/daily_temperatures.ml b/lib/ocaml/baseline/daily_temperatures.ml
new file mode 100644
index 00000000..8996168b
--- /dev/null
+++ b/lib/ocaml/baseline/daily_temperatures.ml
@@ -0,0 +1,24 @@
+let daily_temperatures temps =
+  let n = Array.length temps in
+  let answer = Array.make n 0 in
+  let stack = ref [] in
+  for i = 0 to n - 1 do
+    let cont = ref true in
+    while !cont do
+      match !stack with
+      | top :: rest when temps.(top) < temps.(i) ->
+        answer.(top) <- i - top;
+        stack := rest
+      | _ -> cont := false
+    done;
+    stack := i :: !stack
+  done;
+  let sum = ref 0 in
+  for i = 0 to n - 1 do
+    sum := !sum + answer.(i)
+  done;
+  !sum
+
+;;
+
+daily_temperatures [| 73; 74; 75; 71; 69; 72; 76; 73 |]
diff --git a/lib/ocaml/baseline/expected.json b/lib/ocaml/baseline/expected.json
index 7259d399..33932e5d 100644
--- a/lib/ocaml/baseline/expected.json
+++ b/lib/ocaml/baseline/expected.json
@@ -39,6 +39,7 @@
   "count_palindromes.ml": 9,
   "count_subarrays_k.ml": 7,
   "csv.ml": 10,
+  "daily_temperatures.ml": 10,
   "egg_drop.ml": 8,
   "dijkstra.ml": 7,
   "dp_word_break.ml": 4,
diff --git a/plans/ocaml-on-sx.md b/plans/ocaml-on-sx.md
index 943d0d44..defa645b 100644
--- a/plans/ocaml-on-sx.md
+++ b/plans/ocaml-on-sx.md
@@ -407,6 +407,16 @@ _Newest first._
   binary search tree (`type 'a tree = Leaf | Node of 'a * 'a tree *
   'a tree`) with insert + in-order traversal. Tests parametric ADT,
   recursive match, List.append, List.fold_left.
+- 2026-05-11 Phase 5.1 — daily_temperatures.ml baseline (monotonic
+  decreasing stack of waiting days until warmer; sum over
+  [73;74;75;71;69;72;76;73] = 10). For each day i, pop all stack
+  entries whose temperature is strictly less than today's,
+  recording `i - top` for each. Result vector [1,1,4,2,1,1,0,0]
+  sums to 10. Complementary to next_greater.ml — same monotonic-
+  stack skeleton but stores the distance to the next greater
+  element instead of its value. Tests pattern `match !stack with
+  | top :: rest when condition -> … | _ -> exit` inside while.
+  198 baseline programs total.
 - 2026-05-11 Phase 5.1 — count_bits.ml baseline (sum of popcount for
   0..100 = 319). DP recurrence: popcount(i) = popcount(i/2) +
   (i mod 2) — drop the low bit and recurse, adding back the bit