std::binary_search
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<metanoindex/>
<tbody> </tbody>| Definido no cabeçalho <algorithm>
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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) | |
Verifica se o
[first, last) intervalo classificado contém um elemento igual a value. A primeira versão utiliza operator< para comparar os elementos, a segunda versão utiliza a função de comparação dada comp.Original:
Checks if the sorted range
[first, last) contains an element equal to value. The first version uses operator< to compare the elements, the second version uses the given comparison function comp.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Parâmetros
| first, last | - | a gama de elementos para examinar
Original: the range of elements to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| value | - | valor a comparar os elementos de
Original: value to compare the elements to The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| comp | - | comparison function which returns true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
-ForwardIt must meet the requirements of ForwardIterator.
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Valor de retorno
true se um elemento igual a value é encontrada, de outro modo.. falseOriginal:
true if an element equal to value is found, false otherwise.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Complexidade
Logarítmica na distância entre
first e lastOriginal:
Logarithmic in the distance between
first and lastThe text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Possível implementação
| 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));
}
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| 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));
}
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Exemplo
#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";
}
}
}
Saída:
Searching for 1
Found 1
Searching for 2
no dice!
Searching for 3
Found 3