-
Notifications
You must be signed in to change notification settings - Fork 0
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Same Tree #45
Open
rihib
wants to merge
1
commit into
main
Choose a base branch
from
same_tree
base: main
Could not load branches
Branch not found: {{ refName }}
Loading
Could not load tags
Nothing to show
Loading
Are you sure you want to change the base?
Some commits from the old base branch may be removed from the timeline,
and old review comments may become outdated.
+49
−0
Open
Same Tree #45
Changes from all commits
Commits
File filter
Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,29 @@ | ||
//lint:file-ignore U1000 Ignore all unused code | ||
package sametree | ||
|
||
type TreeNode struct { | ||
Val int | ||
Left *TreeNode | ||
Right *TreeNode | ||
} | ||
|
||
/* | ||
レビュワーの方へ: | ||
- このコードは既にGoの標準のフォーマッタで整形済みです。演算子の周りにスペースがあったりなかったりしますが、これはGoのフォーマッタによるもので、優先順位の高い演算子の周りにはスペースが入らず、低い演算子の周りには入るようになっています。https://qiita.com/tchssk/items/77030b4271cd192d0347 | ||
*/ | ||
|
||
/* | ||
時間:3分30秒 | ||
*/ | ||
func isSameTreeStep1(p *TreeNode, q *TreeNode) bool { | ||
if p == nil && q == nil { | ||
return true | ||
} | ||
if p == nil || q == nil { | ||
return false | ||
} | ||
if p.Val != q.Val { | ||
return false | ||
} | ||
return isSameTreeStep1(p.Left, q.Left) && isSameTreeStep1(p.Right, q.Right) | ||
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,20 @@ | ||
//lint:file-ignore U1000 Ignore all unused code | ||
package sametree | ||
|
||
/* | ||
レビュワーの方へ: | ||
- このコードは既にGoの標準のフォーマッタで整形済みです。演算子の周りにスペースがあったりなかったりしますが、これはGoのフォーマッタによるもので、優先順位の高い演算子の周りにはスペースが入らず、低い演算子の周りには入るようになっています。https://qiita.com/tchssk/items/77030b4271cd192d0347 | ||
*/ | ||
|
||
/* | ||
リファクタした。 | ||
*/ | ||
func isSameTreeStep2(p *TreeNode, q *TreeNode) bool { | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. Iterative DFS/BFSでも書けますか? There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. 再帰をループに直すのは、練習としてわりと重要度高いと個人的には思っています。機会があれば、手の運動くらいの気持ちで。 |
||
if p == nil && q == nil { | ||
return true | ||
} | ||
if p == nil || q == nil || p.Val != q.Val { | ||
return false | ||
} | ||
return isSameTreeStep2(p.Left, q.Left) && isSameTreeStep2(p.Right, q.Right) | ||
} |
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
ある木が木の集合中に存在するかを調べたいという問題だったらどうしますか?このクエリは複数回発行されるものとします。
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
検索を効率化するために例えば下記のように木全体をハッシュ化するなどはいかがでしょうか。
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
この問題とは関係ないですが、木の全ての部分木もハッシュ化したいならどうしますか?全ての部分木に対してpre-order traversalをするのは効率が悪そうです。
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
post-orderで下から順に各ノードでハッシュを計算し、親ノードは左右子ノードのハッシュ値を使ってハッシュを計算するという形にするのが良さそうな気がしました。
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
in-orderではないですか?
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
すみません。post-orderですね。
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
https://en.wikipedia.org/wiki/Merkle_tree
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
ありがとうございます。全く考えてなかったことなので勉強になりました。
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Merkle treeというのがあるのですね、、