DFS_全排列

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <vector>
#define sc(x) scanf("%d",&(x))
#define sc2(x,y) scanf("%d%d", &(x), &(y))
#define pn printf("%
")
#define PF(x) printf("%d ",x)
#define pf(x) printf("%d
",x)
#define CL(x, y) memset(x, y, sizeof(x))
#define FOR(i,b,e)  for(int i = b; i <= e; i++)
#define max(a, b) (a > b ? a : b)
#define ABS(a, b) (a > b ? a - b : b - a)
using namespace std;
const int MAX = 25;
int ans[MAX], used[MAX], n, N = 0;
void show();
void DFS(int pos);
int main()
{
    sc(n);
    CL(used, 0);
    DFS(0);
    cout << "种类为：" << N << endl;
    return 0;
}
void DFS(int pos)
{
    if(pos == n)
    {
        show();
        N++;
        return ;
    }
    FOR(i,1,n)
    {
        if(!used[i])
        {
            used[i] = 1;
            ans[pos] = i;
            DFS(pos+1);
            used[i] = 0;
        }
    }
}
void show()
{
    FOR(j,0,n-1)
    PF(ans[j]);
    cout << endl;
}

 如果直接求种类还是很好办的，到那时其他必须给予数组，或者字符串

string解决

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <vector>
#define sc(x) scanf("%d",&(x))
#define sc2(x,y) scanf("%d%d", &(x), &(y))
#define pn printf("%
")
#define PF(x) printf("%d ",x)
#define pf(x) printf("%d
",x)
#define CL(x, y) memset(x, y, sizeof(x))
#define FOR(i,b,e)  for(int i = b; i <= e; i++)
#define max(a, b) (a > b ? a : b)
#define ABS(a, b) (a > b ? a - b : b - a)
using namespace std;
const int MAX = 25;
int n, N = 1, tmp, j;
string str;
char num[MAX];
int main()
{
    sc(n);
    FOR(i,0,n-1)
    {
        sc(tmp);
        sprintf(num, "%d", tmp);//将数字转化为字符串，可以替代 itoa
        str.append(num);
    }
    sort(str.begin(), str.end());
    cout << str << endl;
    while (next_permutation(str.begin(), str.end()))
    {
        N++;
        cout << str << endl;
    }
    cout << "种类为：" << N << endl;
    return 0;
}

char解决

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <vector>
#define sc(x) scanf("%d",&(x))
#define sc2(x,y) scanf("%d%d", &(x), &(y))
#define pn printf("%
")
#define PF(x) printf("%d ",x)
#define pf(x) printf("%d
",x)
#define CL(x, y) memset(x, y, sizeof(x))
#define FOR(i,b,e)  for(int i = b; i <= e; i++)
#define max(a, b) (a > b ? a : b)
#define ABS(a, b) (a > b ? a - b : b - a)
using namespace std;
const int MAX = 25;
int n, N = 1, tmp;
char ans[MAX], x[MAX];
int main()
{
    sc(n);
    FOR(i,0,n-1)
    {
        sc(tmp);
        sprintf(x, "%d", tmp);
        ans[i] = *x;//x[0]也可以
    }
    sort(ans, ans + n);
    cout << ans << endl;
    while(next_permutation(ans, ans+n))
    {
        N++;
        cout << ans << endl;
    }
    cout << "种类为：" << N << endl;
    return 0;
}