Problem p02720 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;

// #define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int> P;
#define stop                                                                   \
  char nyaa;                                                                   \
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);

ll mod_pow(ll a, ll n, ll m = mod) {
  ll res = 1;
  while (n) {
    if (n & 1)
      res = res * a % m;
    a = a * a % m;
    n >>= 1;
  }
  return res;
}

struct modint {
  ll n;
  modint() : n(0) { ; }
  modint(ll m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod)
    a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0)
    a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((ll)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0)
    return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2)
    res = res * a;
  return res;
}

ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); }
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
const int max_n = 10000;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b)
    return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}

int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

bool used[10][11];
ll dp[10][11];

ll dfs(int t, int p) {
  if (t < 0)
    return 0;
  if (used[t][p])
    return dp[t][p];
  used[t][p] = true;
  ll res = 0;
  if (p == 10) {
    if (t == 0)
      res = 9;
    else {
      res += dfs(t - 1, 10);
      rep1(i, 9) { res += dfs(t - 1, i); }
    }
  } else {
    if (t == 0) {
      if (p > 0)
        res++;
      res++;
      if (p + 1 < 10)
        res++;
    } else {
      if (p > 0) {
        res += dfs(t - 1, p - 1);
      }
      res += dfs(t - 1, p);
      if (p + 1 < 10) {
        res += dfs(t - 1, p + 1);
      }
    }
  }
  return dp[t][p] = res;
}
void solve() {
  ll k;
  cin >> k;
  string ans;
  int sta;
  rep(i, 10) {
    if (k <= dfs(i, 10)) {
      sta = i;
      break;
    }
  }
  if (k < 10) {
    cout << k << "\n";
    return;
  }
  if (k == dfs(sta, 10)) {
    rep(i, sta + 1) ans.push_back('9');
    cout << ans << "\n";
    return;
  }
  // cout << "??? " << sta << "\n";
  k -= dfs(sta - 1, 10);
  int pre = -1;
  for (int i = sta; i > 0; i--) {
    // cout << "?? " << k << "\n";
    rep(j, 10) {
      if (i == sta && j == 0)
        continue;
      if (pre >= 0 && abs(pre - j) > 1)
        continue;
      if (k <= dfs(i - 1, j)) {
        ans.push_back('0' + j);
        pre = j;
        break;
      } else {
        k -= dfs(i - 1, j);
      }
    }
  }
  if (ans.back() == '0')
    ans.push_back(ans.back() - 1 + k);
  else
    ans.push_back(ans.back() - 2 + k);
  for (char c : ans)
    assert('0' <= c && c <= '9');
  cout << ans << "\n";

  // cout << dfs(4, 10) << "\n";
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(7);
  // init_f();
  // init();
  int t;
  cin >> t;
  rep(i, t) solve();
  // solve();
  stop return 0;
}


Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <ciso646>
#include <cmath>
#include <complex>
#include <cstdio>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using namespace std;

// #define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int> P;
#define stop                                                                   \
  char nyaa;                                                                   \
  cin >> nyaa;
#define rep(i, n) for (int i = 0; i < n; i++)
#define per(i, n) for (int i = n - 1; i >= 0; i--)
#define Rep(i, sta, n) for (int i = sta; i < n; i++)
#define rep1(i, n) for (int i = 1; i <= n; i++)
#define per1(i, n) for (int i = n; i >= 1; i--)
#define Rep1(i, sta, n) for (int i = sta; i <= n; i++)
#define all(v) (v).begin(), (v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acos(-1.0);

ll mod_pow(ll a, ll n, ll m = mod) {
  ll res = 1;
  while (n) {
    if (n & 1)
      res = res * a % m;
    a = a * a % m;
    n >>= 1;
  }
  return res;
}

struct modint {
  ll n;
  modint() : n(0) { ; }
  modint(ll m) : n(m) {
    if (n >= mod)
      n %= mod;
    else if (n < 0)
      n = (n % mod + mod) % mod;
  }
  operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint &a, modint b) {
  a.n += b.n;
  if (a.n >= mod)
    a.n -= mod;
  return a;
}
modint operator-=(modint &a, modint b) {
  a.n -= b.n;
  if (a.n < 0)
    a.n += mod;
  return a;
}
modint operator*=(modint &a, modint b) {
  a.n = ((ll)a.n * b.n) % mod;
  return a;
}
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, int n) {
  if (n == 0)
    return modint(1);
  modint res = (a * a) ^ (n / 2);
  if (n % 2)
    res = res * a;
  return res;
}

ll inv(ll a, ll p) { return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p); }
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
const int max_n = 10000;
modint fact[max_n], factinv[max_n];
void init_f() {
  fact[0] = modint(1);
  for (int i = 0; i < max_n - 1; i++) {
    fact[i + 1] = fact[i] * modint(i + 1);
  }
  factinv[max_n - 1] = modint(1) / fact[max_n - 1];
  for (int i = max_n - 2; i >= 0; i--) {
    factinv[i] = factinv[i + 1] * modint(i + 1);
  }
}
modint comb(int a, int b) {
  if (a < 0 || b < 0 || a < b)
    return 0;
  return fact[a] * factinv[b] * factinv[a - b];
}

int dx[4] = {0, 1, 0, -1};
int dy[4] = {1, 0, -1, 0};

bool used[10][11];
ll dp[10][11];

ll dfs(int t, int p) {
  if (t < 0)
    return 0;
  if (used[t][p])
    return dp[t][p];
  used[t][p] = true;
  ll res = 0;
  if (p == 10) {
    if (t == 0)
      res = 9;
    else {
      res += dfs(t - 1, 10);
      rep1(i, 9) { res += dfs(t - 1, i); }
    }
  } else {
    if (t == 0) {
      if (p > 0)
        res++;
      res++;
      if (p + 1 < 10)
        res++;
    } else {
      if (p > 0) {
        res += dfs(t - 1, p - 1);
      }
      res += dfs(t - 1, p);
      if (p + 1 < 10) {
        res += dfs(t - 1, p + 1);
      }
    }
  }
  return dp[t][p] = res;
}
void solve() {
  ll k;
  cin >> k;
  string ans;
  int sta;
  rep(i, 10) {
    if (k <= dfs(i, 10)) {
      sta = i;
      break;
    }
  }
  if (k < 10) {
    cout << k << "\n";
    return;
  }
  if (k == dfs(sta, 10)) {
    rep(i, sta + 1) ans.push_back('9');
    cout << ans << "\n";
    return;
  }
  // cout << "??? " << sta << "\n";
  k -= dfs(sta - 1, 10);
  int pre = -1;
  for (int i = sta; i > 0; i--) {
    // cout << "?? " << k << "\n";
    rep(j, 10) {
      if (i == sta && j == 0)
        continue;
      if (pre >= 0 && abs(pre - j) > 1)
        continue;
      if (k <= dfs(i - 1, j)) {
        ans.push_back('0' + j);
        pre = j;
        break;
      } else {
        k -= dfs(i - 1, j);
      }
    }
  }
  if (ans.back() == '0')
    ans.push_back(ans.back() - 1 + k);
  else
    ans.push_back(ans.back() - 2 + k);
  for (char c : ans)
    assert('0' <= c && c <= '9');
  cout << ans << "\n";

  // cout << dfs(4, 10) << "\n";
}

signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  // cout << fixed << setprecision(7);
  // init_f();
  // init();
  // int t; cin >> t; rep(i, t)solve();
  solve();
  stop return 0;
}