perm1.cpp

来自「C#一个实例源代码」· C++ 代码 · 共 47 行

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include "algostuff.hpp"
using namespace std;

int main()
{
    vector<int> coll;

    INSERT_ELEMENTS(coll,1,3);
    PRINT_ELEMENTS(coll,"on entry:  ");

    /* permute elements until they are sorted
     * - runs through all permutations because the elements are sorted now
     */
    while (next_permutation(coll.begin(),coll.end())) {
        PRINT_ELEMENTS(coll," ");
    }
    PRINT_ELEMENTS(coll,"afterward: ");

    /* permute until descending sorted
     * - this is the next permutation after ascending sorting
     * - so the loop ends immediately
     */
    while (prev_permutation(coll.begin(),coll.end())) {
        PRINT_ELEMENTS(coll," ");
    }
    PRINT_ELEMENTS(coll,"now:       ");

    /* permute elements until they are sorted in descending order
     * - runs through all permutations because the elements are sorted
     *    in descending order now
     */
    while (prev_permutation(coll.begin(),coll.end())) {
        PRINT_ELEMENTS(coll," ");
    }
    PRINT_ELEMENTS(coll,"afterward: ");
}