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From: Junio C Hamano <gitster@pobox•com>
To: Samuel Lijin <sxlijin@gmail•com>
Cc: "git\@vger.kernel.org" <git@vger•kernel.org>
Subject: Re: [PATCH v3 4/8] dir: hide untracked contents of untracked dirs
Date: Wed, 17 May 2017 19:14:26 +0900	[thread overview]
Message-ID: <xmqqfug3x01p.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <CAJZjrdXVzYZ_77Eod6oq-CB+tn5wdF4B3nWzN5zQvjduL9Lnfw@mail.gmail.com> (Samuel Lijin's message of "Wed, 17 May 2017 03:32:09 -0400")

Samuel Lijin <sxlijin@gmail•com> writes:

>>         /* And our single-liner comments look like this */
>>
>>> +             for (i = 0; i < dir->nr; i++) {
>>> +                     if (!dir->entries[i])
>>> +                             continue;
>>> +
>>> +                     for (j = i + 1; j < dir->nr; j++) {
>>> +                             if (!dir->entries[j])
>>> +                                     continue;
>>> +                             if (check_contains(dir->entries[i], dir->entries[j])) {
>>> +                                     nr_removed++;
>>> +                                     free(dir->entries[j]);
>>> +                                     dir->entries[j] = NULL;
>>> +                             }
>>> +                             else {
>>> +                                     break;
>>> +                             }
>>> +                     }
>>> +             }
>>
>> This loop is O(n^2).  I wonder if we can do better, especially we
>> know dir->entries[] is sorted already.
>
> Now that I think about it, dropping an `i = j - 1` into the inner loop
> right before the break should work:

Actually, I think you should be able to do this in a single loop and
write in such a way that it is clearly O(N), perhaps like:

	for (src = dst = 0; src < nr; src++) {
		if (!dst ||
		    !is_a_directory(array[dst - 1]) ||
		    !contains(array[dst - 1], array[src])) {
			array[dst++] = array[src];
		} else {
	                /* 
	                 * Otherwise, src is inside (dst-1), so 
			 * we just can discard it.
			 */
			free(array[src]);
			array[src] = NULL; /* not needed */
		}
	}
	nr = dst;

That is, dst points at the next place to save the final elements of
the array, and dst-1 is the last one that is known to be the final
set.  src points at the element we are inspecting.

If dst-1 does not exist (i.e. we are looking at the first element),
if dst-1 is not a directory, or if dst-1 does not contain the src,
then we need to keep the src in the final set. Otherwise we discard.

  reply	other threads:[~2017-05-17 10:14 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-28 22:56 Bug Report: .gitignore behavior is not matching in git clean and git status Chris Johnson
2017-05-01  1:41 ` Junio C Hamano
2017-05-01  1:56   ` Chris Johnson
2017-05-01  3:15     ` Junio C Hamano
2017-05-01 13:51     ` Samuel Lijin
2017-05-01 15:34       ` Samuel Lijin
2017-05-02  0:26         ` Junio C Hamano
2017-05-03  3:29           ` [PATCH 0/7] Keep git clean -d from inadvertently removing ignored files Samuel Lijin
2017-05-03  3:29             ` [PATCH 1/7] t7300: skip untracked dirs containing " Samuel Lijin
2017-05-03 18:19               ` Stefan Beller
2017-05-03 18:26                 ` Samuel Lijin
2017-05-03 18:34                   ` Stefan Beller
2017-05-03  3:29             ` [PATCH 2/7] dir: recurse into untracked dirs for " Samuel Lijin
2017-05-03  3:29             ` [PATCH 3/7] dir: add method to check if a dir_entry lexically contains another Samuel Lijin
2017-05-03 18:09               ` Stefan Beller
2017-05-03  3:29             ` [PATCH 4/7] dir: hide untracked contents of untracked dirs Samuel Lijin
2017-05-03  3:29             ` [PATCH 5/7] dir: change linkage of cmp_name() and check_contains() Samuel Lijin
2017-05-03  3:29             ` [PATCH 6/7] builtin/clean: teach clean -d to skip dirs containing ignored files Samuel Lijin
2017-05-03  3:29             ` [PATCH 7/7] t7061: check for ignored file in untracked dir Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 0/9] Keep git clean -d from inadvertently removing ignored files Samuel Lijin
2017-05-08  4:26               ` Junio C Hamano
2017-05-08 21:37                 ` Samuel Lijin
2017-05-09  0:31                   ` Junio C Hamano
2017-05-16  7:34               ` [PATCH v3 0/8] Fix clean -d and status --ignored Samuel Lijin
2017-05-18  8:21                 ` [PATCH v4 0/6] " Samuel Lijin
2017-05-23  9:18                   ` [PATCH v5 " Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 " Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 1/6] t7300: clean -d should skip dirs with ignored files Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 2/6] t7061: status --ignored should search untracked dirs Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 3/6] dir: recurse into untracked dirs for ignored files Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 4/6] dir: hide untracked contents of untracked dirs Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 5/6] dir: expose cmp_name() and check_contains() Samuel Lijin
2017-05-23 10:09                     ` [PATCH v6 6/6] clean: teach clean -d to preserve ignored paths Samuel Lijin
2017-05-23 22:35                       ` Junio C Hamano
2017-05-24  4:14                       ` Torsten Bögershausen
2017-05-25 15:36                         ` Samuel Lijin
2017-05-26  1:05                           ` Junio C Hamano
2017-05-23  9:18                   ` [PATCH v5 1/6] t7300: clean -d should skip dirs with ignored files Samuel Lijin
2017-05-23  9:18                   ` [PATCH v5 2/6] t7061: status --ignored should search untracked dirs Samuel Lijin
2017-05-23  9:18                   ` [PATCH v5 3/6] dir: recurse into untracked dirs for ignored files Samuel Lijin
2017-05-23  9:18                   ` [PATCH v5 4/6] dir: hide untracked contents of untracked dirs Samuel Lijin
2017-05-23  9:18                   ` [PATCH v5 5/6] dir: expose cmp_name() and check_contains() Samuel Lijin
2017-05-23  9:18                   ` [PATCH v5 6/6] clean: teach clean -d to preserve ignored paths Samuel Lijin
2017-05-23 12:52                     ` Junio C Hamano
2017-05-23 19:16                       ` Samuel Lijin
2017-05-18  8:21                 ` [PATCH v4 1/6] t7300: clean -d should skip dirs with ignored files Samuel Lijin
2017-05-18  8:21                 ` [PATCH v4 2/6] t7061: status --ignored should search untracked dirs Samuel Lijin
2017-05-18  8:21                 ` [PATCH v4 3/6] dir: recurse into untracked dirs for ignored files Samuel Lijin
2017-05-18  8:21                 ` [PATCH v4 4/6] dir: hide untracked contents of untracked dirs Samuel Lijin
2017-05-22  3:13                   ` Junio C Hamano
2017-05-18  8:21                 ` [PATCH v4 5/6] dir: expose cmp_name() and check_contains() Samuel Lijin
2017-05-22  0:38                   ` Junio C Hamano
2017-05-18  8:21                 ` [PATCH v4 6/6] clean: teach clean -d to skip dirs containing ignored files Samuel Lijin
2017-05-22  4:48                   ` Junio C Hamano
2017-05-22  5:58                     ` Samuel Lijin
2017-05-22  6:17                       ` Junio C Hamano
2017-05-23  2:43                         ` Samuel Lijin
2017-05-23  7:50                           ` Junio C Hamano
2017-05-16  7:34               ` [PATCH v3 1/8] t7300: clean -d should skip dirs with " Samuel Lijin
2017-05-16  7:34               ` [PATCH v3 2/8] t7061: status --ignored should search untracked dirs Samuel Lijin
2017-05-16  7:34               ` [PATCH v3 3/8] dir: recurse into untracked dirs for ignored files Samuel Lijin
2017-05-17  6:23                 ` Junio C Hamano
2017-05-17  7:02                   ` Samuel Lijin
2017-05-16  7:34               ` [PATCH v3 4/8] dir: hide untracked contents of untracked dirs Samuel Lijin
2017-05-17  6:47                 ` Junio C Hamano
2017-05-17  7:32                   ` Samuel Lijin
2017-05-17 10:14                     ` Junio C Hamano [this message]
2017-05-16  7:34               ` [PATCH v3 5/8] dir: expose cmp_name() and check_contains() Samuel Lijin
2017-05-16  7:34               ` [PATCH v3 6/8] clean: teach clean -d to skip dirs containing ignored files Samuel Lijin
2017-05-18  2:34                 ` Junio C Hamano
2017-05-18  6:32                   ` Samuel Lijin
2017-05-16  7:34               ` [PATCH v3 7/8] t7300: clean -d now skips untracked " Samuel Lijin
2017-05-18  2:38                 ` Junio C Hamano
2017-05-16  7:34               ` [PATCH v3 8/8] t7061: status --ignored now searches untracked dirs Samuel Lijin
2017-05-18  2:46                 ` Junio C Hamano
2017-05-05 10:46             ` [PATCH v2 1/9] t7300: skip untracked dirs containing ignored files Samuel Lijin
2017-05-07 19:12               ` Torsten Bögershausen
2017-05-08 21:24                 ` Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 2/9] t7061: expect failure where expected behavior will change Samuel Lijin
2017-05-08  4:34               ` Junio C Hamano
2017-05-05 10:46             ` [PATCH v2 3/9] dir: recurse into untracked dirs for ignored files Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 4/9] dir: add method to check if a dir_entry lexically contains another Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 5/9] dir: hide untracked contents of untracked dirs Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 6/9] dir: change linkage of cmp_name() and check_contains() Samuel Lijin
2017-05-08  4:37               ` Junio C Hamano
2017-05-05 10:46             ` [PATCH v2 7/9] builtin/clean: teach clean -d to skip dirs containing ignored files Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 8/9] t7300: clean -d now skips untracked " Samuel Lijin
2017-05-05 10:46             ` [PATCH v2 9/9] t7061: expect ignored files in untracked dirs Samuel Lijin
2017-05-08  6:35               ` Junio C Hamano

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