StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
13729871
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2012-12-05T18:23:33.487
FavoriteCount
0
LastActivityDate
2017-05-24T23:14:28.943
LastEditDate
2017-05-24T23:14:28.943
LastEditorUserId
300908
OwnerUserId
300908
ParentId
13628191
PostTypeId
2
Score
11
ViewCount
0
LastEditorDisplayName
text
Body
I wanted to come up with a solution that did not loop over the collection N times and I believe I've found a novel divide and conquer approach: <pre><code>int n0_, n1_, n2_, n3_, n4_, n5_, n6_, n7_; // Input data int n0 = 0; int n1 = 64; int n2 = 8; int n3 = 8; int n4 = 0; int n5 = 12; int n6 = 224; int n7 = 0; //Subdivide into four groups of 2 (trivial to solve each pair) n0_ = n0 & n1; n1_ = n0 | n1; n2_ = n2 & n3; n3_ = n2 | n3; n4_ = n4 & n5; n5_ = n4 | n5; n6_ = n6 & n7; n7_ = n6 | n7; //Merge into two groups of 4 n0 = (n0_ & n2_); n1 = (n0_ & n3_) | (n1_ & n2_); n2 = (n0_ | n2_) | (n1_ & n3_); n3 = (n1_ | n3_); n4 = (n4_ & n6_); n5 = (n4_ & n7_) | (n5_ & n6_); n6 = (n4_ | n6_) | (n5_ & n7_); n7 = (n5_ | n7_); //Merge into final answer n0_ = (n0 & n4); n1_ = (n0 & n5) | (n1 & n4); n2_ = (n0 & n6) | (n1 & n5) | (n2 & n4); n3_ = (n0 & n7) | (n1 & n6) | (n2 & n5) | (n3 & n4); n4_ = (n0) | (n1 & n7) | (n2 & n6) | (n3 & n5) | (n4); n5_ = (n1) | (n2 & n7) | (n3 & n6) | (n5); n6_ = (n2) | (n3 & n7) | (n6); n7_ = (n3 | n7); </code></pre> This approach requires just 56 bitwise operations, which is considerably fewer than the other solutions provided. It is important to understand the cases in which bits will be set in the final answer. For example, a column in n5 is 1 if there are three or more bits set in that column. These bits can arranged in any order, which makes counting them efficiently fairly difficult. The idea is to break the problem into sub-problems, solve the sub-problems and then merge the solutions together. Every time we merge two blocks, we know the bits will have been correctly "dropped" in each. This means we won't have to check every possible permutation of bits at each stage. Although I didn't realize it until now, this is really similar to Merge Sort which capitalizes on sorted sub-arrays when merging. 
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POBitwise operation exercise
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USJoshVarty
UserOwnerUserId
1. USJoshVarty
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.