std::is_sorted_until - cppreference.com

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Elemento definito nell'header `<algorithm>`

`template< class ForwardIt > ForwardIt is_sorted_until( ForwardIt first, ForwardIt last );`	(1)	(dal C++11)

`template< class ForwardIt, class Compare > ForwardIt is_sorted_until( ForwardIt first, ForwardIt last, Compare comp );`	(2)	(dal C++11)

Esamina l'[first, last) campo e trova l'inizio più vasta gamma di first in cui vengono ordinati gli elementi in ordine crescente. La prima versione della funzione utilizza operator< per confrontare gli elementi, il secondo utilizza la funzione di confronto dato comp.

Original:

Examines the range [first, last) and finds the largest range beginning at first in which the elements are sorted in ascending order. The first version of the function uses operator< to compare the elements, the second uses the given comparison function comp.

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Parametri

first, last	-	la gamma di elementi da esaminare 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.
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: `bool cmp(const Type1 &a, const Type2 &b);` The signature does not need to have `const &`, but the function must not modify the objects passed to it. The types `Type1` and `Type2` must be such that an object of type `ForwardIterator` can be dereferenced and then implicitly converted to both of them.
Type requirements
-`ForwardIt` must meet the requirements of `ForwardIterator`.

Valore di ritorno

Il limite superiore di inizio più vasta gamma di first in cui vengono ordinati gli elementi in ordine crescente. Cioè, il it iteratore ultimo per il quale è ordinato [first, it) gamma.

Original:

The upper bound of the largest range beginning at first in which the elements are sorted in ascending order. That is, the last iterator it for which range [first, it) is sorted.

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Complessità

lineare la distanza tra first e last

Original:

linear in the distance between first and last

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Possibile implementazione

First version
template<class ForwardIt> ForwardIt is_sorted_until(ForwardIt first, ForwardIt last) { if (first != last) { ForwardIt next = first; while (++next != last) { if (next < first) return next; first = next; } } return last; }
Second version
template< class ForwardIt, class Compare > ForwardIt is_sorted_until(ForwardIt first, ForwardIt last, Compare comp) { if (first != last) { ForwardIt next = first; while (++next != last) { if (comp(next, first)) return next; first = next; } } return last;

First version

template<class ForwardIt>
ForwardIt is_sorted_until(ForwardIt first, ForwardIt last)
{
    if (first != last) {
        ForwardIt next = first;
        while (++next != last) {
            if (*next < *first)
                return next;
            first = next;
        }
    }
    return last;
}

Second version

template< class ForwardIt, class Compare >
ForwardIt is_sorted_until(ForwardIt first, ForwardIt last, 
                          Compare comp)
{
    if (first != last) {
        ForwardIt next = first;
        while (++next != last) {
            if (comp(*next, *first))
                return next;
            first = next;
        }
    }
    return last;

Esempio

#include <iostream>
#include <algorithm>
#include <iterator>
#include <random>

int main()
{
    std::random_device rd;
    std::mt19937 g(rd());
    const int N = 6;
    int nums[N] = {3, 1, 4, 1, 5, 9};

    const int min_sorted_size = 4;
    int sorted_size = 0;
    do {
        std::random_shuffle(nums, nums + N, g);
        int *sorted_end = std::is_sorted_until(nums, nums + N);
        sorted_size = std::distance(nums, sorted_end);

        for (auto i : nums) std::cout << i << ' ';
        std::cout << " : " << sorted_size << " initial sorted elements\n";
    } while (sorted_size < min_sorted_size);
}

Possible output:

4 1 9 5 1 3  : 1 initial sorted elements
4 5 9 3 1 1  : 3 initial sorted elements
9 3 1 4 5 1  : 1 initial sorted elements
1 3 5 4 1 9  : 3 initial sorted elements
5 9 1 1 3 4  : 2 initial sorted elements
4 9 1 5 1 3  : 2 initial sorted elements
1 1 4 9 5 3  : 4 initial sorted elements

Vedi anche


	controlla se un intervallo è ordinata in ordine ascendente Original: checks whether a range is sorted into ascending order The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello) [modifica]