ソースコード
// 基本テンプレート
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
using namespace std;
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define repq(i,a,n) for(int (i)=(a); (i)<=(n); (i)++)
#define repr(i,a,n) for(int (i)=(a); (i)>=(n); (i)--)
#define debug(...) fprintf(stderr, __VA_ARGS__)
#define int long long int
template<typename T> void chmax(T &a, T b) {a = max(a, b);}
template<typename T> void chmin(T &a, T b) {a = min(a, b);}
template<typename T> void chadd(T &a, T b) {a = a + b;}
typedef pair<int, int> pii;
typedef long long ll;
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
const ll INF = 1001001001001001LL;
const ll MOD = 1000000007LL;
const int MAXD = 1000;
int dp[1010][1010];
signed main() {
int N, K; cin >> N >> K;
dp[0][0] = 1;
for(int i=0; i<MAXD; i++) {
for(int j=0; j<=N; j++) {
for(int d=0; d<10; d++) {
dp[i+1][j+d] = min(INF, dp[i+1][j+d] + dp[i][j]);
}
}
}
string ans = "";
int sum = N, rest = K;
bool leading_zero = true;
// fprintf(stderr, "rest = %lld\n", rest);
for(int dig=MAXD; dig>=0; dig--) {
for(int d=0; d<10; d++) {
if(sum-d < 0) continue;
// printf("dig = %lld, d = %lld, dp = %lld, rest = %lld\n", dig, d, dp[dig][sum-d], rest);
if(dp[dig][sum-d] >= rest) {
// printf("dig = %lld, d = %lld\n", dig, d);
if(leading_zero == true && d > 0) {
leading_zero = false;
}
if(!leading_zero) {
ans += ('0' + d);
}
sum -= d;
break;
}
else {
rest -= dp[dig][sum-d];
}
}
}
fprintf(stderr, "rest = %lld\n", rest);
cout << ans << endl;
return 0;
}