枚举排列的两种常见方法

1、递归枚举

 1 #include<iostream>
 2 using namespace std;
 3
 4 void print_permutation(int n, int *p, int cur)
 5 {
 6     if (cur == n)
 7     {
 8         for (int i = 0; i < n; i++)
 9             cout << p[i];
10         cout << endl;
11     }
12     else for (int i = 1; i <= n; i++)
13     {
14         int ok = 1;
15         for (int j = 0; j < cur; j++)
16         if (p[j] == i)  ok = 0;
17         if (ok)
18         {
19             p[cur] = i;
20             print_permutation(n, p, cur + 1);
21         }
22     }
23 }
24 int _tmain(int argc, _TCHAR* argv[])
25 {
26     int n,p[10000],cur=0;
27     cin >> n;
28     print_permutation(n, p, cur);
29     return 0;
30 }

2、STL——next_permutation

 1 #include<iostream>
 2 #include<algorithm>
 3 using namespace std;
 4
 5 int _tmain(int argc, _TCHAR* argv[])
 6 {
 7     int n, p[10];
 8     cin >> n;
 9     for (int i = 0; i < n; i++)
10         cin >> p[i];
11     sort(p, p + n);
12     do{
13         for (int i = 0; i < n; i++)
14             cout << p[i];
15         cout << endl;
16     } while (next_permutation(p, p + n));
17     return 0;
18 }