正整数从1到N，输出按照字典序排序的前K个数

#include <iostream>
#include <cassert>

using namespace std;

const int max_len = ;

char a[max_len];

void topK(int n, int m, int& k, int i)
{
    if (k <=  || i >= m)
        return;
    for (int j = ; j < ; j++)
    {
        a[i] = j + '';
        a[i+] = '\0';
        int v = atoi(a);
        if (v >  && v <= n && k > )
        {
            cout << a << endl;
            k--;
            topK(n, m, k, i+1);
        }
    }
}

void topK(int n, int k)
{
    assert(n >= );
    int m = ;
    int p = n;
    while (p > )
    {
        m++;
        p /= ;
    }
    topK(n, m, k, );
}

int main()
{
    topK(, );
    return ;
}