枚举排列

#include <iostream>
using namespace std;
#define N 1001
int rcd
;
int used
;
int num
;
int n;
void permutation(int l)
{
if(l == n)
{
for(int i = 0; i < n; i++)
{
cout << rcd[i] << " ";
}
cout << endl;
}
else
{
for(int i = 0; i < n; i++)
{
if (!used[i])
{
used[i] = 1;
rcd[l] = num[i];
permutation(l + 1);
used[i] = 0;
}
}
}
}
int readData()
{
int i;
if( scanf("%d", &n) == EOF)
{
return 0;
}
for(int i = 0; i < n; i++) scanf("%d", &num[i]);
for(int i = 0; i < n; i++) used[i] = 0;
return 1;
}
int main()
{
while(readData())
{
permutation(0);
}
}

#include <iostream>
using namespace std;
#define N 1001
int rcd
;
int used
;
int num
;
int n;
int m;
void unrepeatPermutation(int l)
{
if(l == n)
{
for(int i = 0; i < n; i++)
{
cout << rcd[i] << " ";
}
cout << endl;
}
else
{
for(int i = 0; i < m; i++)
{
if (used[i] > 0)
{
used[i]--;
rcd[l] = num[i];
unrepeatPermutation(l + 1);
used[i]++;
}
}
}
}
int readData()
{
int i, j, val;
if( scanf("%d", &n) == EOF)
{
return 0;
}
m = 0;
for(int i = 0; i < n; i++)
{
scanf("%d", &val);
for(j = 0; j < m; j++)
{
if(num[j] == val)
{
used[j]++;
break;
}
}
if(j == m)
{
num[m] = val;
used[m] = 1;
m++;
}
}
return 1;
}
int main()
{
while(readData())
{
unrepeatPermutation(0);
}
}

// next_permutation
#include <iostream>
#include <algorithm>
using namespace std;
int main () {
int myints[] = {1,1,2};
cout << "The possible permutations with 3 elements:/n";
sort (myints,myints+3);
do {
cout << myints[0] << " " << myints[1] << " " << myints[2] << endl;
} while ( next_permutation (myints,myints+3) );
return 0;
}

The possible permutations with 3 elements:
1 1 2
1 2 1
2 1 1