func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 20 + 5;   const long long INF = 3e9;   const char *cc =  0123456789abcdef ;   int c[maxn][maxn], used[maxn];   long long dp[maxn][maxn];   char s[maxn];   long long solve(int t, int m, bool flag) {     memset(dp[0], 0, sizeof(dp[0]));     if (flag) {       for (int i = 0; i < m; ++i) {         for (int j = 0; j + used[0] <= t && j + i + 1 <= m; ++j) {           dp[0][i + j] = min(INF, dp[0][i + j] + c[m - i - 1][j]);         }       }     } else       for (int i = 0; i + used[0] <= t && i <= m; ++i) dp[0][i] = c[m][i];     for (int i = 1; i < 16; ++i) {       memset(dp[i], 0, sizeof(dp[i]));       for (int j = 0; j <= m; ++j) {         if (!dp[i - 1][j]) continue;         for (int k = 0; k + used[i] <= t && k + j <= m; ++k) {           dp[i][j + k] = min(INF, dp[i][j + k] + dp[i - 1][j] * c[m - j][k]);         }       }     }     return dp[15][m];   }   int main() {     for (int i = 0; i < maxn; ++i) {       c[i][0] = c[i][i] = 1;       for (int j = 1; j < i; ++j) c[i][j] = c[i - 1][j - 1] + c[i - 1][j];     }     int k, t;     cin >> k >> t;     bool flag = true;     for (int i = 0; i < 20; ++i) {       long long sum = 0;       for (int j = 0; j < 16; ++j) {         if (used[j] >= t) continue;         if (!flag || j != 0) ++used[j];         long long tmp = solve(t, 20 - i - 1, flag && j == 0);         sum += tmp;         if (sum >= k) {           s[i] = cc[j];           k -= sum - tmp;           if (j > 0) flag = false;           break;         }         if (!flag || j != 0) --used[j];       }     }     s[20] = 0;     int p = 0;     while (s[p] ==  0 ) ++p;     cout << s + p << endl;     return 0;   }   