C++全排列

1.函数next_permutation  

 #include <algorithm>

int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};//要先排好顺序

do{
    for (int j = 0; j < 9; ++j) {
        cout << a[j] << " ";
    }
    cout << endl;
}while (next_permutation(a,a+9));

2.手写函数

void f(int k) {
        for (int i = k; i < 9; ++i) {
        {int t = a[i];a[i] = a[k];a[k] = t;}
        for (int j = 0; j < 9; ++j) {
            cout << a[j] << " ";
        }
        cout << endl;
        f(k + 1);
        {int t = a[i];a[i] = a[k];a[k] = t;}
    }
}