枚举生成和子集生成

#include <stdio.h>

int main()
{
    int n,i , j, a[100], a1[100];
    while(scanf("%d", &n) == 1)
    {
        for(i = 0; i<n; i++)
        {
            scanf("%d", &a1[i]);
        }

        for (i = n-1; i>0; i--)
        {
            for (j = 0; j<i; j++)
            {
                if (a1[j] > a1[j+1])
                {
                    int t;
                    t = a1[j];
                    a1[j] = a1[j+1];
                    a1[j+1] = t;
                }
            }
        }
        print_permutation(a, a1, n, 0);
    }
}

void print_permutation(int *a, int *a1, int n, int cur)
{
    int i;
    if (cur == n)
    {
        for (i = 0; i<n; i++)
        {
            printf("%d ", a[i]);
        }

        printf("
");
    }
    else
    {
        for (i = 0; i<n; i++)
        {
            int j, ok = 1;
            for (j = 0; j<cur; j++)
            {
                if (a[j] == a1[i])
                {
                    ok = 0;
                    break;
                }
            }

            if (ok)
            {
                a[cur] = a1[i];
                print_permutation(a, a1, n, cur+1);
            }
        }
    }
}

#include <stdio.h>

int main()
{
    int n,i , j, a[100], a1[100];
    while(scanf("%d", &n) == 1)
    {
        for(i = 0; i<n; i++)
        {
            scanf("%d", &a1[i]);
        }

        for (i = n-1; i>0; i--)
        {
            for (j = 0; j<i; j++)
            {
                if (a1[j] > a1[j+1])
                {
                    int t;
                    t = a1[j];
                    a1[j] = a1[j+1];
                    a1[j+1] = t;
                }
            }
        }
        print_permutation(a, a1, n, 0);
    }
}

void print_permutation(int *a, int *a1, int n, int cur)
{
    int i;
    if (cur == n)
    {
        for (i = 0; i<n; i++)
        {
            printf("%d ", a[i]);
        }

        printf("
");
    }
    else
    {
        for (i = 0; i<n; i++)
            if( !i || a1[i]!=a1[i-1])
        {
            int j, c1 = 0, c2  =0, ok = 1;
            for (j = 0; j<cur; j++) if (a[j] == a1[i]) c1++;
            for (j = 0; j<n; j++) if (a1[j] == a1[i]) c2++;
            if (c1<c2)
            {
                a[cur] = a1[i];
                print_permutation(a, a1, n, cur+1);
            }
        }
    }
}