std::next_permutation
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Defined in header <algorithm> | ||
template<class BidirIt > bool next_permutation( BidirIt first, BidirIt last ); | (1) | |
template<class BidirIt, class Compare > bool next_permutation( BidirIt first, BidirIt last, Compare comp ); | (2) | |
Trasforma il
[first, last)
campo nella prossima permutazione dall'insieme di tutte le permutazioni che sono classificati in ordine lessicografico rispetto al operator<
o comp
. true Restituisce se esiste permutazione, trasforma altrimenti il campo nella prima permutazione (come per std::sort(first, last)
) e ritorna false.Original:
Transforms the range
[first, last)
into the next permutation from the set of all permutations that are lexicographically ordered with respect to operator<
or comp
. Returns true if such permutation exists, otherwise transforms the range into the first permutation (as if by std::sort(first, last)
) and returns false.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.
Indice |
[modifica]Parametri
first, last | - | la gamma di elementi per permutare Original: the range of elements to permute 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. |
Type requirements | ||
-BidirIt must meet the requirements of ValueSwappable and BidirectionalIterator . |
[modifica]Valore di ritorno
true se la permutazione nuovo lessicograficamente maggiore del vecchio. false se la permutazione ultimo è stato raggiunto e la gamma è stato reimpostato per la permutazione prima.
Original:
true if the new permutation is lexicographically greater than the old. false if the last permutation was reached and the range was reset to the first permutation.
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[modifica]Complessità
Alla maggior parte degli swap N/2, dove N =std::distance(first, last).
Original:
At most N/2 swaps, where N =std::distance(first, last).
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[modifica]Possibile implementazione
template<class BidirIt>bool next_permutation(BidirIt first, BidirIt last){if(first == last)returnfalse; BidirIt i = last;if(first ==--i)returnfalse; while(1){ BidirIt i1, i2; i1 = i;if(*--i <*i1){ i2 = last;while(!(*i <*--i2));std::iter_swap(i, i2);std::reverse(i1, last);returntrue;}if(i == first){std::reverse(first, last);returnfalse;}}} |
[modifica]Esempio
Il codice seguente consente di stampare tutte e tre le permutazioni della stringa "aba"
Original:
The following code prints all three permutations of the string "aba"
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#include <algorithm>#include <string>#include <iostream> int main(){std::string s ="aba";std::sort(s.begin(), s.end());do{std::cout<< s <<'\n';}while(std::next_permutation(s.begin(), s.end()));}
Output:
aab aba baa
[modifica]Vedi anche
(C++11) | determines if a sequence is a permutation of another sequence (funzione di modello) |
generates the next smaller lexicographic permutation of a range of elements (funzione di modello) |