Permutation Generator source code

This snippet submitted by Treenef on 2005-08-23. It has been viewed 38411 times.
Rating of 5.7 with 456 votes

/*==================================
  A program which gives a lexigraphic
  permutation generator.
  - An alternative to using the STL
  and #include <algorithm>
  ==================================*/
#include <iostream>

//Function declarations
void Permute(int [],int,int);
void Print(int [],int);
void Swap(int [],int,int);
void Rotate_Left(int v[],int,int);

using namespace std;
int main()
{
    int N;
    cout<<"Please enter 'N'"<<endl;
    cout<<">>";
    cin>>N;
    
    int v[100];
    for (int i=0; i<N; i++)
    {
        v[i]=i+1;//initialise
    }
    Permute(v,0,N);
    cin.get();
    cin.get();
    
    return 0;
}
/*==================================
  Function  Permute
  ==================================*/
void Permute(int v[],int start, int n)
{
    Print(v,n);
    if (start<n)
    {
        int i,j;
        for(i=n-2; i>=start; i--)
        {
            for(j=i+1; j<n; j++)
            {
                Swap(v,i,j);
                Permute(v,i+1,n);
            }
            Rotate_Left(v,i,n);
        }
    }
}

/*==============================
  Function Print
  =============================*/
void Print(int v[],int size)
{
    if (v!=0)
    {
        for (int i=0; i<size; i++)
        {
            cout<<v[i];
        }
        cout<<""<<endl;
    }
}

/*==============================
  Function swap
  ==============================*/
void Swap(int v[],int i,int j)
{
    int t;
    t = v[i];
    v[i] = v[j];
    v[j] = t;
}

/*===========================
  Function rotate left
  ===========================*/
void Rotate_Left(int v[],int go,int n)
{
    int tmp = v[go];
    for (int i=go; i<n-1; i++)
    {
        v[i] = v[i+1];
    }
    v[n-1] = tmp;
}                           




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