Use rotate to rotate two elements to the right : rotate « STL Algorithms Modifying sequence operations « C++ Tutorial






/* 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 <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>

/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << ' ';
    }
    std::cout << std::endl;
}

/* INSERT_ELEMENTS (collection, first, last)
 * - fill values from first to last into the collection
 * - NOTE: NO half-open range
 */
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
    for (int i=first; i<=last; ++i) {
        coll.insert(coll.end(),i);
    }
}

using namespace std;

int main()
{
    vector<int> coll;

    INSERT_ELEMENTS(coll,1,9);
    PRINT_ELEMENTS(coll,"coll:      ");

    // rotate two elements to the right
    rotate (coll.begin(),      // beginning of range
            coll.end() - 2,    // new first element
            coll.end());       // end of range
    PRINT_ELEMENTS(coll,"two right: ");
}
coll:      1 2 3 4 5 6 7 8 9
two right: 8 9 1 2 3 4 5 6 7








24.18.rotate
24.18.1.Use the generic rotate algorithm
24.18.2.Use rotate to rotate one element to the left
24.18.3.Use rotate to rotate two elements to the right
24.18.4.Use rotate to rotate so that element with value 4 is the beginning
24.18.5.Rotate left two places
24.18.6.Rotate a vector: Rotate left one position
24.18.7.Right-rotate a sequence by using reverse iterators with the rotate() algorithm.