C + + recursive position permutation algorithm and its application

Needless to say, let's look at the algorithm for positional sorting:

#include <iostream>using namespace Std;int n = 0;int m = 2;int L = 0;int a[100];void solve (int l); int main () {cout< ;< "Please enter the number of digits n" <<endl;cin>>n;solve (l); return 0;} void solve (int l) {if (l>=n) {for (int i = 0; i<n; i++) {cout<<a[i];} cout << Endl;return;} for (int i = 0; i < m;i++) {A[l] = I;solve (l+1);}}

The results of the operation are as follows:

Please enter the number of digits n
4
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

We can apply this algorithm to such an example:

To recursively find all subsets of a collection:

The code is as follows:

#include <iostream> #include <vector> #include <stdio.h>using namespace std;void solve (int l); int n, M;    int mat[100];vector<string> Collection;int Main () {string firstelement;    string element;    int mcount = 1;    cout << "Please input the element, end by #end" << Endl;    Cin >> Firstelement;         while (firstelement! = "#end") {element = Firstelement;         cout << "The element" <<mcount<< "You are input is" + element<< Endl; Collection.push_back (Element);         cout << collection[mcount-1];         cout << "Please input the next element, end by #end" << Endl;    Cin >> Firstelement;    }n = Collection.size ();    m = 2;    Solve (0); return 0;}    void solve (int l)//l=0{int i;        if (l >= N)//n=4 {printf ("{"); for (i=0; i<n; ++i) {if (mat[i] = = 1) {cout<< collection[i] <<     " ";       }} printf ("}\n");    Return        } for (i=0; i<m; ++i)//m=2 {mat[l] = i;    Solve (l+1); }}

The results of the operation are as follows:

Please input the element, end by #end
A
The element 1 you input is a
Please input the next element, end by #end
B
The element 1 you input is b
Please input the next element, end by #end
C
The element 1 you input is C
Please input the next element, end by #end
#end
{}
C
{B}
{b C}
A
{A c}
{a B}
{a b C}

C + + recursive position permutation algorithm and its application