ソースコード
#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,_7,_8,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr8,pr7,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
using namespace std;
using Int = long long;
using _int = int;
using ll = long long;
using Double = long double;
const Int INF = (1LL<<55)+1e9; // ~ 3.6 * 1e16
const Int mod = (1e9)+7;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
using P = pair<Int,Int>;
using T = tuple<Int,Int,Int>;
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
ostream& operator<<(ostream& o,P p){return o<<"("<<p.first<<","<<p.second<<")";}
ostream& operator<<(ostream& o,T t){return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
istream& operator>>(istream& i,P &p){return i>>p.first>>p.second;}
template<class T> ostream& operator<<(ostream& o,vector<T> &a){Int i=0;for(auto t:a)o<<(i++?" ":"")<<t;return o;}
template<class T> istream& operator>>(istream& i,vector<T> &a){for(auto &t:a)i>>t;return i;}
template<class T> void prArr(T a,string s=" "){Int i=0;for(auto t:a)cout<<(i++?s:"")<<t;cout<<endl;}
const int N = 1010;
int mem[2][N+10][N+10]; //length, sum
int used[2][N+10][N+10];
int n, K;
int dfs(int flag, int len,int sum){
if(sum < 0) return 0;
if(len == 0) return sum == 0 && flag;
if(used[flag][len][sum]++) return mem[flag][len][sum];
Int res = 0;
for(int i=0;i<10;i++){
int nflag = flag | (i!=0);
res += dfs(nflag,len-1, sum-i);
Min(res, INF);
}
return mem[flag][len][sum] = res;
}
string ans;
void dfs2(int flag,int len,int sum,int K){
if(len == 0) assert(sum == 0);
if(len == 0) return;
int num = 0;
int cnt = 0;
for(int i=0;i<10;i++){
num = i;
int nflag = flag | (num!=0);
int a = dfs(nflag, len - 1, sum - num );
if(cnt + a >= K) break;
cnt += a;
}
int nflag = flag | (num!=0);
dfs2(nflag, len-1, sum - num, K - cnt);
ans += char('0' + num);
}
signed main(){
srand((unsigned)time(NULL));
cin.tie(0);
ios_base::sync_with_stdio(0);
cout << fixed << setprecision(12);
cin>>n>>K;
int len = 1;
int sum = 0;
while(1){
int a = dfs(0, len, n);
if(sum + a >= K) break;
sum += a;
len++;
}
dfs2(0, len, n, K);
reverse(ans.begin(), ans.end());
cout<<ans<<endl;
return 0;
}