permuter.h

C++&datastructure书籍源码,以前外教提供现在与大家共享

#ifndef _PERMUTER_H
#define _PERMUTER_H

#include "tvector.h"
#include "prompt.h"

// iterating class for generating permutations one at a time
// each call of Current() returns the "next"
// permutation in lexicographic order, i.e., 
// if "abcde" is initial list, then "abced" is next
// after "edcba" we have "abcde". 
//
// HasMore returns true when the original list is generated
// again (all n! permutations will have been generated)

class Permuter
{
  public:
    Permuter(const tvector<int>& list); 
    
    void Init();
    bool HasMore();
    void Next();
    void Current(tvector<int>& list);
    
  private:
    tvector<int> myList;        // current permutation
    tvector<int> myOriginal;    // copy of original list
    bool         myFirst;       // first permutation?
    
    void Swap(int x1, int x2);
    void Reverse(int first, int last);
};

#endif