std::binary_search

 

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機能します Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
シーケンス動作を非改変 Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_of any_of none_of (C++11) (C++11) (C++11) for_each count count_if mismatch equal	find find_if find_if_not (C++11) find_end find_first_of adjacent_find search search_n
シーケンス動作を変更する Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copy copy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   (C++11) unique unique_copy
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is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
（ソートされた範囲で）ソート操作 Original: Sorting operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
バイナリ検索操作（ソート範囲で） Original: Binary search operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
lower_bound upper_bound	binary_search equal_range
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qsort	bsearch

 

Defined in header <algorithm>
template<class ForwardIt, class T > bool binary_search( ForwardIt first, ForwardIt last, const T& value );	(1)
template<class ForwardIt, class T, class Compare > bool binary_search( ForwardIt first, ForwardIt last, const T& value, Compare comp );	(2)

ソート範囲[first, last)いるかどうかをチェックvalueに等しい要素が含まれています。最初のバージョンは、要素を比較するoperator<使用して、2番目のバージョンは、指定された比較関数compを使用しています.

パラメータ

first, last	-	検討する要素の範囲
value	-	に要素を比較する値
comp	-	比較関数. 最初の値が二つ目の値より小さい 場合、 ​trueを返します. 比較関数のシグネチャは以下と同等でなければなりません.  bool cmp(const Type1 &a, const Type2 &b); シグネチャはconstを含まなくても構いませんが, 比較関数は渡されたオブジェクトを変更してはなりません. The type Type1 must be such that an object of type T can be implicitly converted to Type1. The type Type2 must be such that an object of type ForwardIt can be dereferenced and then implicitly converted to Type2. ​
型の要件
- ForwardIt は ForwardIterator の要求を満足しなければなりません。

返り値

valueに等しい要素が見つかった場合はtrue。その他の場合はfalse。

計算複雑性

firstlastとの間の距離の対数

可能な実装

First version
template<class ForwardIt, class T>bool binary_search(ForwardIt first, ForwardIt last, const T& value){ first =std::lower_bound(first, last, value);return(first != last &&!(value <*first));}
Second version
template<class ForwardIt, class T, class Compare>bool binary_search(ForwardIt first, ForwardIt last, const T& value, Compare comp){ first =std::lower_bound(first, last, value);return(first != last &&!(comp(value, *first));}

例

このコードを実行します

#include <iostream>#include <algorithm>#include <vector>   int main(){std::vector<int> haystack {1, 3, 4, 5, 9};std::vector<int> needles {1, 2, 3};   for(auto needle : needles){std::cout<<"Searching for "<< needle <<'\n';if(std::binary_search(haystack.begin(), haystack.end(), needle)){std::cout<<"Found "<< needle <<'\n';}else{std::cout<<"no dice!\n";}}}

出力:

Searching for 1 Found 1 Searching for 2 no dice! Searching for 3 Found 3

参考

equal_range	特定のキーと一致する要素の範囲を返します Original: returns range of elements matching a specific key The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (関数テンプレート)