完善程序：（排列数）输入两个正整数n, m (

完善程序：（排列数）输入两个正整数n, m (1 ≤n ≤20, 1 ≤m ≤n)，在 1~n 中任取 m 个数，按字典序从小到大输出所有这样的排列。例如

输入

3 2

输出：

1 21 32 12 33 13 2

#include

#include

using namespace std;

const int SIZE = 25;

bool used[SIZE];

int data[SIZE];

int n, m, i,j, k;

bool flag;

int main()

{

\tcin>>n>>m;

\tmemset(used, false, sizeof(used));

\tfor (i = 1; i <= m; i )

\t{

\t\tdata[i] = i;

\t\tused[i] = true;

\t}

\tflag = true;

\twhile (flag)

\t{

\t\tfor (i = 1; i <= m-1; i ) cout<

\t\tcout<

\t\tflag = ① ;

\t\tfor (i = m; i >= 1; i--)

\t\t{

\t\t\t ② ;

\t\t\tfor (j = data[i] 1; j <= n; j ) if (!used[j])

\t\t\t{

\t\t\t\tused[j] = true;

\t\t\t\tdata[i] = ③ ;

\t\t\t\tflag = true;

\t\t\t\tbreak;

\t\t\t}

\t\t\tif (flag)

\t\t\t{

\t\t\t\tfor (k = i 1; k <= m; k )

\t\t\t\t\tfor (j = 1; j <= ④ ; j ) if (!used[j])

\t\t\t\t\t{

\t\t\t\t\t\tdata[k] = j;

\t\t\t\t\t\tused[j] = true;

\t\t\t\t\t\tbreak;

\t\t\t\t\t}

\t\t\t\t\t ⑤ ;

\t\t\t}

\t\t}

\t}

}