prev_permutation (STL Samples)

說明如何使用 prev_permutation Visual C++ 標準樣板程式庫 (STL) 函式。

template<class BidirectionalIterator> inline
   bool prev_permutation(
      BidirectionalIterator First,
      BidirectionalIterator Last
   )

備註

注意事項
在原型中的類別/參數名稱不相符的標頭檔中的版本。某些已修改以提高可讀性。

prev_permutation演算法的範圍變更的元素順序 [First， Last)、 先前的 lexicographic 排列，並傳回 ，則為 true。 如果沒有任何prev_permutation，它將成為第一個排列的順序排列，並傳回 ，則為 false。

注意事項
prev_permutation演算法會假設順序按遞減順序使用運算子 <。Nonpredicate 版本使用運算子 < ，下令排列方式。

範例

// prev_permutation.cpp
// compile with: /EHsc
// Illustrates how to use the prev_permutation
// function.
//
// Functions:
//    prev_permutation : Change the order of the sequence to the
//                       previous lexicographic permutation.

// disable warning C4786: symbol greater than 255 character,
// okay to ignore
#pragma warning(disable: 4786)

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>

using namespace std ;

int main()
{
    const int VECTOR_SIZE = 3;

    // Define a template class vector of strings
    typedef vector<string> StrVector;

    // Define an iterator for template class vector of strings
    typedef StrVector::iterator StrVectorIt;

    // Define an ostream iterator for strings
    typedef ostream_iterator<string>
    StrOstreamIt;

    StrVector Pattern(VECTOR_SIZE);

    StrVectorIt start, end, it;

    StrOstreamIt outIt(cout, " ");

    // location of first element of Pattern
    start = Pattern.begin();

    // one past the location last element of Pattern
    end = Pattern.end();

    //Initialize vector Pattern
    Pattern[0] = "C";
    Pattern[1] = "B";
    Pattern[2] = "A";

    // print content of Pattern
    cout << "Before calling prev_permutation..." << endl << "Pattern: [";
    for (it = start; it != end; it++)
        cout << " " << *it;
    cout << " ]" << endl;

    // Generate all possible permutations
    cout << "After calling prev_permutation...." << endl;
    while ( prev_permutation(start, end) )
    {
        cout << "[ ";
        copy(start, end, outIt);
        cout << "]" << endl;
    }
}

Output

Before calling prev_permutation...
Pattern: [ C B A ]
After calling prev_permutation....
[ C A B ]
[ B C A ]
[ B A C ]
[ A C B ]
[ A B C ]

需求

標頭: <algorithm>

請參閱

概念

標準樣板程式庫範例