An example of dp-digit

#include<bits/stdc++.h>
using namespace std;
long long a, k, dp[20][10][2][2], tmp;
string s;
void read()
{
    cin >> k >> a;
}
long long Count(int pos, int prenum, bool zero, bool low)
{
    if (pos == s.length())
    {
        return 1;
    }
    long long &res = dp[pos][prenum][zero][low];
    if (res != -1)
    {
        return res;
    }
    res = 0;
    int lim = s[pos] - '0';
    if (low)
    {
        lim = 9;
    }
    for (int j = 0; j <= lim; ++ j)
    {
        if (abs(j - prenum) <= 1 || (zero == 0))
        {
            res += Count(pos + 1, j, zero | j, low | (j < (s[pos] - '0')));
        }
    }
    return res;
}
long long Get(long long x)
{
    memset(dp, -1, sizeof(dp));
    s = to_string(x);
    return Count(0,0,0,0);
}
bool check(long long x)
{
    long long cnt = Get(x);
    return cnt - tmp >= k;
}
void solve()
{
    long long low = a + 1, high = 1e18;
    tmp = Get(a);
    while (low <= high)
    {
        long long mid = (low + high)/2;
        if (check(mid))
        {
            high = mid - 1;
        }
        else
        {
            low = mid + 1;
        }
    }
    cout << low;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    read();
    solve();
}