Subject: [PATCH] sparse-checkout: optimize string_list construction

From: amisha <[email-masked]>
Date: Thu, 15 Jan 2026 00:58:03 +0530

Improve O(n^2) complexity to O(n log n) while building a sorted 'string_list' by constructing it unsorted and sorting it afterwards.

Signed-off-by: amisha <[email-masked]>
---
Note for reviewers:
I identified this as a strong candidate for optimization because we are 
pulling entries from a hashmap. Since hashmaps inherently guarantee 
uniqueness of keys, using string_list_append() is safe here.

 builtin/sparse-checkout.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 15d51e60a8..0a44808ed2 100644
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -91,7 +91,7 @@ static int sparse_checkout_list(int argc, const char **argv, const char *prefix,
 
 		hashmap_for_each_entry(&pl.recursive_hashmap, &iter, pe, ent) {
 			/* pe->pattern starts with "/", skip it */
-			string_list_insert(&sl, pe->pattern + 1);
+			string_list_append(&sl, pe->pattern + 1);
 		}
 
 		string_list_sort(&sl);
-- 
2.51.0