sparse-checkout: optimize string_list construction

Improve O(n^2) complexity to O(n log n) while building a sorted
'string_list' by constructing it unsorted then sorting it
followed by removing duplicates.

Signed-off-by: Amisha Chhajed <amishhhaaaa@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
index 15d51e60a865331c63be35523507a315646603aa..7dfb276bf01431b9430693b7b005a49671f20eb7 100644 (file)
--- a/builtin/sparse-checkout.c
+++ b/builtin/sparse-checkout.c
@@ -91,10 +91,11 @@ 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);
+               string_list_remove_duplicates(&sl, 0);
 
                for (i = 0; i < sl.nr; i++) {
                        quote_c_style(sl.items[i].string, NULL, stdout, 0);
@@ -289,7 +290,7 @@ static void write_cone_to_file(FILE *fp, struct pattern_list *pl)
                if (!hashmap_contains_parent(&pl->recursive_hashmap,
                                             pe->pattern,
                                             &parent_pattern))
-                       string_list_insert(&sl, pe->pattern);
+                       string_list_append(&sl, pe->pattern);
        }
 
        string_list_sort(&sl);
@@ -311,7 +312,7 @@ static void write_cone_to_file(FILE *fp, struct pattern_list *pl)
                if (!hashmap_contains_parent(&pl->recursive_hashmap,
                                             pe->pattern,
                                             &parent_pattern))
-                       string_list_insert(&sl, pe->pattern);
+                       string_list_append(&sl, pe->pattern);
        }
 
        strbuf_release(&parent_pattern);