Problem p02716 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;
typedef vector<vector<vector<ll>>> VVV;
typedef vector<vector<vector<vector<ll>>>> VVVV;

#define REP(i, a, b) for (ll i = (a); i < (b); i++)
#define PER(i, a, b) for (ll i = (a); i >= (b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF = 1e18 + 18;
const ll MAX = 100005;
const ll MOD = 1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a, b)
#define Each(a, b) for (auto &a : b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#ifdef LOCAL
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp)                                                             \\
  cerr << #mp << ":" << endl;                                                  \\
  for (auto i = mp.begin(); i != mp.end(); ++i) {                              \\
    cerr << i->first << ":" << i->second << endl;                              \\
  }
#define dbgarr(n, m, arr)                                                      \\
  rep(i, n) {                                                                  \\
    rep(j, m) { cerr << arr[i][j] << " "; }                                    \\
    cerr << endl;                                                              \\
  }
#define dbgdp(n, arr)                                                          \\
  rep(i, n) { cerr << arr[i] << " "; }                                         \\
  cerr << endl;
#define dbgmint(n, arr)                                                        \\
  rep(i, n) { cerr << arr[i].x << " "; }                                       \\
  cerr << endl;
#define dbgarrmint(n, m, arr)                                                  \\
  rep(i, n) {                                                                  \\
    rep(j, m) { cerr << arr[i][j].x << " "; }                                  \\
    cerr << endl;                                                              \\
  }
#else
#define dbg(...)
#define dbgmap(...)
#define dbgarr(...)
#define dbgdp(...)
#define dbgmint(...)
#define dbgarrmint(...)
#endif
#define out(a) cout << a << endl
#define out2(a, b) cout << a << " " << b << endl
#define vout(v)                                                                \\
  rep(i, v.size()) { cout << v[i] << " "; }                                    \\
  cout << endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}

template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) {
  return s << "(" << p.first << ", " << p.second << ")";
}

template <typename T> istream &operator>>(istream &i, vector<T> &v) {
  rep(j, v.size()) i >> v[j];
  return i;
}

// vector
template <typename T> ostream &operator<<(ostream &s, const vector<T> &v) {
  int len = v.size();
  for (int i = 0; i < len; ++i) {
    s << v[i];
    if (i < len - 1)
      s << "	";
  }
  return s;
}

// 2 dimentional vector
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  int len = vv.size();
  for (int i = 0; i < len; ++i) {
    s << vv[i] << endl;
  }
  return s;
}

// mint
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % MOD + MOD) % MOD) {}
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

struct combination {
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < MOD);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << std::setprecision(10);

  ll n;
  cin >> n;
  Vec a(n);
  cin >> a;
  VV dp(n + 1, Vec(4, -INF));
  ll k = 0;
  if (n % 2 == 1) {
    k = 2;
  } else {
    k = 1;
  }
  dp[0][0] = 0;
  rep(i, n) {
    rep(j, k + 1) {
      chmax(dp[i + 1][j + 1], dp[i][j]);
      if ((i + j) % 2 == 0) {
        chmax(dp[i + 1][j], dp[i][j] + a[i]);
      } else {
        chmax(dp[i + 1][j], dp[i][j]);
      }
    }
  }
  out(dp[n][k]);
  return 0;
}


Error: WA

Fixed submission:


#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;
typedef vector<vector<vector<ll>>> VVV;
typedef vector<vector<vector<vector<ll>>>> VVVV;

#define REP(i, a, b) for (ll i = (a); i < (b); i++)
#define PER(i, a, b) for (ll i = (a); i >= (b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF = 1e18 + 18;
const ll MAX = 100005;
const ll MOD = 1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a, b)
#define Each(a, b) for (auto &a : b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#ifdef LOCAL
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp)                                                             \\
  cerr << #mp << ":" << endl;                                                  \\
  for (auto i = mp.begin(); i != mp.end(); ++i) {                              \\
    cerr << i->first << ":" << i->second << endl;                              \\
  }
#define dbgarr(n, m, arr)                                                      \\
  rep(i, n) {                                                                  \\
    rep(j, m) { cerr << arr[i][j] << " "; }                                    \\
    cerr << endl;                                                              \\
  }
#define dbgdp(n, arr)                                                          \\
  rep(i, n) { cerr << arr[i] << " "; }                                         \\
  cerr << endl;
#define dbgmint(n, arr)                                                        \\
  rep(i, n) { cerr << arr[i].x << " "; }                                       \\
  cerr << endl;
#define dbgarrmint(n, m, arr)                                                  \\
  rep(i, n) {                                                                  \\
    rep(j, m) { cerr << arr[i][j].x << " "; }                                  \\
    cerr << endl;                                                              \\
  }
#else
#define dbg(...)
#define dbgmap(...)
#define dbgarr(...)
#define dbgdp(...)
#define dbgmint(...)
#define dbgarrmint(...)
#endif
#define out(a) cout << a << endl
#define out2(a, b) cout << a << " " << b << endl
#define vout(v)                                                                \\
  rep(i, v.size()) { cout << v[i] << " "; }                                    \\
  cout << endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}

template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) {
  return s << "(" << p.first << ", " << p.second << ")";
}

template <typename T> istream &operator>>(istream &i, vector<T> &v) {
  rep(j, v.size()) i >> v[j];
  return i;
}

// vector
template <typename T> ostream &operator<<(ostream &s, const vector<T> &v) {
  int len = v.size();
  for (int i = 0; i < len; ++i) {
    s << v[i];
    if (i < len - 1)
      s << "	";
  }
  return s;
}

// 2 dimentional vector
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  int len = vv.size();
  for (int i = 0; i < len; ++i) {
    s << vv[i] << endl;
  }
  return s;
}

// mint
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % MOD + MOD) % MOD) {}
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

struct combination {
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < MOD);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << std::setprecision(10);

  ll n;
  cin >> n;
  string s;
  cin >> s;
  VV g(3);
  rep(i, n) {
    if (s[i] == 'R')
      g[0].pb(i);
    if (s[i] == 'G')
      g[1].pb(i);
    if (s[i] == 'B')
      g[2].pb(i);
  }
  dbg(g);
  ll ans = g[0].size() * g[1].size() * g[2].size();
  dbg(ans);
  ll R = g[0].size();
  ll G = g[1].size();
  Vec B = g[2];
  rep(i, R) {
    rep(j, G) {
      ll x = g[0][i];
      ll y = g[1][j];
      if (x > y)
        swap(x, y);
      ll z1 = 2 * y - x;
      ll z2 = 2 * x - y;
      if (binary_search(ALL(B), z1))
        ans--;
      if (binary_search(ALL(B), z2))
        ans--;
      if ((x + y) % 2 == 0) {
        ll z3 = (x + y) / 2;
        if (binary_search(ALL(B), z3))
          ans--;
      }
    }
  }
  cout << ans << endl;
  return 0;
}