Problem p02692 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;

#define LL long long
// #define LL __int64
typedef pair<int, int> pii;

template <typename T> inline void read(T &x) {
  static char _c;
  static bool _f;

  x = 0;
  _f = 0;
  _c = getchar();

  while (_c < '0' || '9' < _c) {
    if (_c == '-')
      _f = true;
    _c = getchar();
  }
  while ('0' <= _c && _c <= '9') {
    x = (x << 1) + (x << 3) + (_c & 15);
    _c = getchar();
  }
  if (_f)
    x = -x;
}
template <typename T, typename... Args> inline void read(T &x, Args &...args) {
  read(x);
  read(args...);
}

template <typename T> inline void Min(T &x, T y) {
  if (y < x)
    x = y;
}
template <typename T> inline void Max(T &x, T y) {
  if (x < y)
    x = y;
}

#define lowbit(x) ((x) & -(x))
#define lson l, mid, id << 1
#define rson mid + 1, r, id << 1 | 1
#define ls id << 1
#define rs id << 1 | 1
#define MID(l, r) ((l) + (((r) - (l)) >> 1))
#define fi first
#define se second
#define mk make_pair
#define mt make_tuple
#define pb push_back

const int INF = 0x3f3f3f3f;
const LL LINF = 0x3f3f3f3f3f3f3f3f;
const double pi = (double)acos(-1.0);
const double eps = (double)1e-8;
const int e5 = (int)1e5 + 5;
const int MOD = (int)1e9 + 7;
// const int MOD = (int) 998244353;
// int MOD = 998244353;

template <typename T0, typename T1>
inline void depair(T0 &x, T1 &y, pair<T0, T1> &p) {
  x = p.fi, y = p.se;
}
inline int sig(double x) { return x < -eps ? -1 : eps < x; }
LL fp(LL a, LL n, LL mod = MOD) {
  if (n < 0)
    a = fp(a, mod - 2, mod), n = -n;
  LL res = 1;
  for (; n; n >>= 1, a = a * a % mod)
    if (n & 1)
      res = res * a % mod;
  return res;
}

struct Mint {
  int x;
  Mint() { x = 0; }
  Mint(int _x) : x(_x) {
    if (x < 0 || x >= MOD)
      x = (x % MOD + MOD) % MOD;
  }
  Mint(LL _x) : x(_x) {
    if (x < 0 || x >= MOD)
      x = (x % MOD + MOD) % MOD;
  }
  Mint operator-() const { return Mint(MOD - x); }
  Mint operator+(const Mint &rhs) const {
    return Mint(x + rhs.x >= MOD ? x + rhs.x - MOD : x + rhs.x);
  }
  Mint operator-(const Mint &rhs) const {
    return Mint(x - rhs.x < 0 ? x - rhs.x + MOD : x - rhs.x);
  }
  Mint operator*(const Mint &rhs) const { return Mint((LL)x * rhs.x % MOD); }
  Mint operator/(const Mint &rhs) const {
    return Mint(x * fp(rhs.x, -1) % MOD);
  }
  Mint &operator+=(const Mint &rhs) {
    x += rhs.x;
    if (x >= MOD)
      x -= MOD;
    return *this;
  }
  Mint &operator*=(const Mint &rhs) {
    x = ((LL)x * rhs.x) % MOD;
    return *this;
  }
  bool operator==(const Mint &rhs) const { return x == rhs.x; }
  bool operator!=(const Mint &rhs) const { return x != rhs.x; }
  friend ostream &operator<<(ostream &out, const Mint &rhs) {
    return out << rhs.x;
  }
  friend istream &operator>>(istream &in, Mint &rhs) { return in >> rhs.x; }
};

const int maxn = (int)2e5 + 20;
const int maxm = (int)1e6 + 20;

int n;
int a, b, c;
vector<string> vs;

void work() {
  cin >> n;
  cin >> a >> b >> c;
  vs = vector<string>(n + 1);
  for (int i = 1; i <= n; i++)
    cin >> vs[i];

  if ((LL)a + b + c != 2) {
    int flag = 1;
    vector<char> ans;
    for (int i = 1; i <= n; i++) {
      if (vs[i] == "AB") {
        if (a == 0 && b == 0) {
          flag = 0;
          break;
        }

        if (a > b) {
          a--;
          b++;
          ans.pb('B');
        } else {
          a++;
          b--;
          ans.pb('A');
        }
      } else if (vs[i] == "AC") {
        if (a == 0 && c == 0) {
          flag = 0;
          break;
        }

        if (a > c) {
          a--;
          c++;
          ans.pb('C');
        } else {
          a++;
          c--;
          ans.pb('A');
        }
      } else {
        if (b == 0 && c == 0) {
          flag = 0;
          break;
        }

        if (b > c) {
          b--;
          c++;
          ans.pb('C');
        } else {
          b++;
          c--;
          ans.pb('B');
        }
      }
    }
    if (flag) {
      cout << "Yes" << endl;
      for (auto c : ans)
        cout << c << endl;
    } else {
      cout << "No" << endl;
    }
  } else {
    vector<vector<int>> dp(n + 1, vector<int>(27, 0));

    auto encode = [](int x, int y, int z) { return (x * 3 + y) * 3 + z; };
    auto decode = [](int c, int &x, int &y, int &z) {
      z = c % 3;
      c /= 3;
      y = c % 3;
      c /= 3;
      x = c;
    };

    int en = encode(a, b, c);
    dp[0][en] = 1;
    //        cout <<en <<endl;

    for (int i = 1; i <= n; i++) {
      for (int j = 0; j < 27; j++) {
        if (!dp[i - 1][j])
          continue;

        //                cout <<i <<" " <<j <<endl;

        int a, b, c;
        decode(j, a, b, c);

        if (vs[i] == "AB") {
          if (a)
            dp[i][encode(a - 1, b + 1, c)] = j;
          if (b)
            dp[i][encode(a + 1, b - 1, c)] = j;
        } else if (vs[i] == "AC") {
          if (a)
            dp[i][encode(a - 1, b, c + 1)] = j;
          if (c)
            dp[i][encode(a + 1, b, c - 1)] = j;
        } else {
          if (b)
            dp[i][encode(a, b - 1, c + 1)] = j;
          if (c)
            dp[i][encode(a, b + 1, c - 1)] = j;
        }
      }
    }

    int flag = -1;
    for (int j = 0; j < 27; j++)
      if (dp[n][j]) {
        flag = j;
        break;
      }

    if (flag == -1) {
      cout << "No" << endl;
      return;
    }

    //        cout <<flag <<endl;

    stack<char> s;
    for (int i = n, j = flag; i; j = dp[i--][j]) {
      int pj = dp[i][j];
      int a, b, c, x, y, z;
      decode(j, a, b, c);
      decode(pj, x, y, z);

      if (a > x)
        s.push('A');
      if (b > y)
        s.push('B');
      if (c > z)
        s.push('C');

      //            cout <<i <<" " <<j <<endl;
    }

    cout << "Yes" << endl;
    while (!s.empty()) {
      cout << s.top() << endl;
      s.pop();
    }
  }
}

int main(int argc, char **argv) {
#ifdef yukihana0416
  freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
#endif // yukihana0416
       //    get_prime();
       //    pre();
  int tc = 1;
  //    read(tc);
  for (int ca = 1; ca <= tc; ca++) {
    //        printf("Case #%d: ", ca);
    work();
  }
  return 0;
}


Error: WA

Fixed submission:

#include <bits/stdc++.h>
using namespace std;

#define LL long long
// #define LL __int64
typedef pair<int, int> pii;

template <typename T> inline void read(T &x) {
  static char _c;
  static bool _f;

  x = 0;
  _f = 0;
  _c = getchar();

  while (_c < '0' || '9' < _c) {
    if (_c == '-')
      _f = true;
    _c = getchar();
  }
  while ('0' <= _c && _c <= '9') {
    x = (x << 1) + (x << 3) + (_c & 15);
    _c = getchar();
  }
  if (_f)
    x = -x;
}
template <typename T, typename... Args> inline void read(T &x, Args &...args) {
  read(x);
  read(args...);
}

template <typename T> inline void Min(T &x, T y) {
  if (y < x)
    x = y;
}
template <typename T> inline void Max(T &x, T y) {
  if (x < y)
    x = y;
}

#define lowbit(x) ((x) & -(x))
#define lson l, mid, id << 1
#define rson mid + 1, r, id << 1 | 1
#define ls id << 1
#define rs id << 1 | 1
#define MID(l, r) ((l) + (((r) - (l)) >> 1))
#define fi first
#define se second
#define mk make_pair
#define mt make_tuple
#define pb push_back

const int INF = 0x3f3f3f3f;
const LL LINF = 0x3f3f3f3f3f3f3f3f;
const double pi = (double)acos(-1.0);
const double eps = (double)1e-8;
const int e5 = (int)1e5 + 5;
const int MOD = (int)1e9 + 7;
// const int MOD = (int) 998244353;
// int MOD = 998244353;

template <typename T0, typename T1>
inline void depair(T0 &x, T1 &y, pair<T0, T1> &p) {
  x = p.fi, y = p.se;
}
inline int sig(double x) { return x < -eps ? -1 : eps < x; }
LL fp(LL a, LL n, LL mod = MOD) {
  if (n < 0)
    a = fp(a, mod - 2, mod), n = -n;
  LL res = 1;
  for (; n; n >>= 1, a = a * a % mod)
    if (n & 1)
      res = res * a % mod;
  return res;
}

struct Mint {
  int x;
  Mint() { x = 0; }
  Mint(int _x) : x(_x) {
    if (x < 0 || x >= MOD)
      x = (x % MOD + MOD) % MOD;
  }
  Mint(LL _x) : x(_x) {
    if (x < 0 || x >= MOD)
      x = (x % MOD + MOD) % MOD;
  }
  Mint operator-() const { return Mint(MOD - x); }
  Mint operator+(const Mint &rhs) const {
    return Mint(x + rhs.x >= MOD ? x + rhs.x - MOD : x + rhs.x);
  }
  Mint operator-(const Mint &rhs) const {
    return Mint(x - rhs.x < 0 ? x - rhs.x + MOD : x - rhs.x);
  }
  Mint operator*(const Mint &rhs) const { return Mint((LL)x * rhs.x % MOD); }
  Mint operator/(const Mint &rhs) const {
    return Mint(x * fp(rhs.x, -1) % MOD);
  }
  Mint &operator+=(const Mint &rhs) {
    x += rhs.x;
    if (x >= MOD)
      x -= MOD;
    return *this;
  }
  Mint &operator*=(const Mint &rhs) {
    x = ((LL)x * rhs.x) % MOD;
    return *this;
  }
  bool operator==(const Mint &rhs) const { return x == rhs.x; }
  bool operator!=(const Mint &rhs) const { return x != rhs.x; }
  friend ostream &operator<<(ostream &out, const Mint &rhs) {
    return out << rhs.x;
  }
  friend istream &operator>>(istream &in, Mint &rhs) { return in >> rhs.x; }
};

const int maxn = (int)2e5 + 20;
const int maxm = (int)1e6 + 20;

int n;
int a, b, c;
vector<string> vs;

void work() {
  cin >> n;
  cin >> a >> b >> c;
  vs = vector<string>(n + 1);
  for (int i = 1; i <= n; i++)
    cin >> vs[i];

  if (a + b + c != 2) {
    int flag = 1;
    vector<char> ans;
    for (int i = 1; i <= n; i++) {
      if (vs[i] == "AB") {
        if (a == 0 && b == 0) {
          flag = 0;
          break;
        }

        if (a > b) {
          a--;
          b++;
          ans.pb('B');
        } else {
          a++;
          b--;
          ans.pb('A');
        }
      } else if (vs[i] == "AC") {
        if (a == 0 && c == 0) {
          flag = 0;
          break;
        }

        if (a > c) {
          a--;
          c++;
          ans.pb('C');
        } else {
          a++;
          c--;
          ans.pb('A');
        }
      } else {
        if (b == 0 && c == 0) {
          flag = 0;
          break;
        }

        if (b > c) {
          b--;
          c++;
          ans.pb('C');
        } else {
          b++;
          c--;
          ans.pb('B');
        }
      }
    }
    if (flag) {
      cout << "YES" << endl;
      for (auto c : ans)
        cout << c << endl;
    } else {
      cout << "NO" << endl;
    }
  } else {
    vector<vector<int>> dp(n + 1, vector<int>(9, 0));

    auto encode = [](int x, int y, int z) { return (x * 3 + y) * 3 + z; };
    auto decode = [](int c, int &x, int &y, int &z) {
      z = c % 3;
      c /= 3;
      y = c % 3;
      c /= 3;
      x = c;
    };

    int en = encode(a, b, c);
    dp[0][en] = 1;

    for (int i = 1; i <= n; i++) {
      for (int j = 0; j < 9; j++) {
        if (!dp[i - 1][j])
          continue;

        int a, b, c;
        decode(j, a, b, c);

        if (vs[i] == "AB") {
          if (a)
            dp[i][encode(a - 1, b + 1, c)] = j;
          if (b)
            dp[i][encode(a + 1, b - 1, c)] = j;
        } else if (vs[i] == "AC") {
          if (a)
            dp[i][encode(a - 1, b, c + 1)] = j;
          if (c)
            dp[i][encode(a + 1, b, c - 1)] = j;
        } else {
          if (b)
            dp[i][encode(a, b - 1, c + 1)] = j;
          if (c)
            dp[i][encode(a, b + 1, c - 1)] = j;
        }
      }
    }

    int flag = -1;
    for (int j = 0; j < 9; j++)
      if (!dp[n][j]) {
        flag = j;
        break;
      }

    if (flag == -1) {
      cout << "NO" << endl;
      return;
    }

    stack<char> s;
    for (int i = n, j = flag; i; j = dp[i--][j]) {
      int pj = dp[i][j];
      int a, b, c, x, y, z;
      decode(j, a, b, c);
      decode(pj, x, y, z);

      if (a < x)
        s.push('A');
      if (b < y)
        s.push('B');
      if (c < z)
        s.push('C');
    }

    cout << "YES" << endl;
    while (!s.empty()) {
      cout << s.top() << endl;
      s.pop();
    }
  }
}

int main(int argc, char **argv) {
#ifdef yukihana0416
  freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
#endif // yukihana0416
       //    get_prime();
       //    pre();
  int tc = 1;
  //    read(tc);
  for (int ca = 1; ca <= tc; ca++) {
    //        printf("Case #%d: ", ca);
    work();
  }
  return 0;
}