std::min_element
Da cppreference.com.
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<tbody> </tbody>| Elemento definito nell'header <algorithm>
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template< class ForwardIt > ForwardIt min_element( ForwardIt first, ForwardIt last ); |
(1) | |
template< class ForwardIt, class Compare > ForwardIt min_element( ForwardIt first, ForwardIt last, Compare comp ); |
(2) | |
Trova il più piccolo elemento nel
[first, last) gamma. La prima versione utilizza operator< per confrontare i valori, la seconda versione utilizza la funzione di confronto dato comp.Original:
Finds the smallest element in the range
[first, last). The first version uses operator< to compare the values, 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.
Parametri
| first, last | - | iteratori forward che definiscono l'intervallo di esaminare
Original: forward iterators defining the range to examine The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| cmp | - | comparison function which returns true if if *a is less than *b. 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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Valore di ritorno
Iterator al più piccolo elemento nel
[first, last) gamma. Se diversi elementi della gamma sono equivalenti al più piccolo elemento, restituisce l'iteratore al primo elemento tale. Restituisce last se il campo è vuoto.Original:
Iterator to the smallest element in the range
[first, last). If several elements in the range are equivalent to the smallest element, returns the iterator to the first such element. Returns last if the range is empty.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.
Complessità
Esattamente max(N-1,0) confronti,
N = std::distance(first, last) dove.Original:
Exactly max(N-1,0) comparisons, where
N = std::distance(first, last).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.
Possibile implementazione
| First version |
|---|
template<class ForwardIt>
ForwardIt min_element(ForwardIt first, ForwardIt last)
{
if (first == last) return last;
ForwardIt smallest = first;
++first;
for (; first != last; ++first) {
if (*first < *smallest) {
smallest = first;
}
}
return smallest;
}
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| Second version |
template<class ForwardIt, class Compare>
ForwardIt min_element(ForwardIt first, ForwardIt last,
Compare comp)
{
if (first == last) return last;
ForwardIt smallest = first;
++first;
for (; first != last; ++first) {
if (comp(*first, *smallest)) {
smallest = first;
}
}
return smallest;
}
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Esempio
#include <algorithm>
#include <iostream>
#include <vector>
int main()
{
std::vector<int> v{3, 1, 4, 1, 5, 9};
std::vector<int>::iterator result = std::min_element(v.begin(), v.end());
std::cout << "min element at: " << std::distance(v.begin(), result);
}
Output:
min element at: 1