Problem p02679 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

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

ll gcd(ll n, ll m) {
  ll tmp;
  while (m != 0) {
    tmp = n % m;
    n = m;
    m = tmp;
  }
  return n;
}

ll lcm(ll n, ll m) {
  return abs(n) / gcd(n, m) * abs(m); // gl=xy
}

using namespace std;

template <int mod> struct ModInt {
  int x;

  ModInt() : x(0) {}

  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }

  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }

  ModInt operator-() const { return ModInt(-x); }

  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

  bool operator==(const ModInt &p) const { return x == p.x; }

  bool operator!=(const ModInt &p) const { return x != p.x; }

  bool operator>=(const ModInt &p) const { return x >= p.x; }
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }

  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }

  friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }

  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }

  static int get_mod() { return mod; }
};

using modint = ModInt<mod>;

using P = pair<ll, ll>;
void solve() {
  int n;
  cin >> n;
  ll zero = 0, z = 0, z2 = 0;
  vector<ll> a(n), b(n);
  rep(i, n) cin >> a[i] >> b[i];
  map<P, ll> mp;
  rep(i, n) {
    if ((a[i] != 0) && (b[i] != 0)) {
      ll x = gcd(abs(a[i]), abs(b[i]));
      if (b[i] < 0) {
        a[i] = -a[i];
        b[i] = -b[i];
      }
      mp[P{a[i] / x, b[i] / x}]++;
    } else if ((a[i] == 0) && (b[i] == 0)) {
      ++zero;
    } else if (a[i] == 0) {
      z++;
    } else {
      z2++;
    }
  }
  modint ans = 1;
  ll cnt = n - zero - z - z2;
  for (auto x : mp) {
    if (mp.count(P{-x.first.second, x.first.first})) {
      modint s = 2;
      s = s.pow(x.second);
      modint t = 2;
      t = t.pow(mp[P{-x.first.second, x.first.first}]);
      ans *= (s + t - 1);
      cnt -= x.second + mp[P{-x.first.second, x.first.first}];
    }
  }
  modint x = 2;
  x = x.pow(cnt);
  ans *= x;
  x = 2;
  x = x.pow(z);
  modint y = 2;
  y = y.pow(z2);
  ans *= (x + y - 1);
  ans -= 1;    // 何も選ばないはなし
  ans += zero; // a=0,b=0のものは一匹ずつなら選べる
  cout << ans << endl;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(15);
  solve();
  return 0;
}


Error: -6
fd1dc60d-12ab-4a3a-9815-f3ed82bace1f.out: /home/alex/Documents/bug-detection/input/Project_CodeNet/data/p02679/C++/s745887687.cpp:167: void solve(): Assertion `cnt < 0' failed.


Fixed submission:

#include <bits/stdc++.h>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

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

ll gcd(ll n, ll m) {
  ll tmp;
  while (m != 0) {
    tmp = n % m;
    n = m;
    m = tmp;
  }
  return n;
}

ll lcm(ll n, ll m) {
  return abs(n) / gcd(n, m) * abs(m); // gl=xy
}

using namespace std;

template <int mod> struct ModInt {
  int x;

  ModInt() : x(0) {}

  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

  ModInt &operator+=(const ModInt &p) {
    if ((x += p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator-=(const ModInt &p) {
    if ((x += mod - p.x) >= mod)
      x -= mod;
    return *this;
  }

  ModInt &operator*=(const ModInt &p) {
    x = (int)(1LL * x * p.x % mod);
    return *this;
  }

  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }

  ModInt operator-() const { return ModInt(-x); }

  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

  bool operator==(const ModInt &p) const { return x == p.x; }

  bool operator!=(const ModInt &p) const { return x != p.x; }

  bool operator>=(const ModInt &p) const { return x >= p.x; }
  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while (b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }

  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while (n > 0) {
      if (n & 1)
        ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }

  friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }

  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt<mod>(t);
    return (is);
  }

  static int get_mod() { return mod; }
};

using modint = ModInt<mod>;

using P = pair<ll, ll>;
void solve() {
  int n;
  cin >> n;
  ll zero = 0, z = 0, z2 = 0;
  vector<ll> a(n), b(n);
  rep(i, n) cin >> a[i] >> b[i];
  map<P, ll> mp;
  rep(i, n) {
    if ((a[i] != 0) && (b[i] != 0)) {
      ll x = gcd(abs(a[i]), abs(b[i]));
      if (b[i] < 0) {
        a[i] = -a[i];
        b[i] = -b[i];
      }
      mp[P{a[i] / x, b[i] / x}]++;
    } else if ((a[i] == 0) && (b[i] == 0)) {
      ++zero;
    } else if (a[i] == 0) {
      z++;
    } else {
      z2++;
    }
  }
  modint ans = 1;
  ll cnt = n - zero - z - z2;
  for (auto x : mp) {
    if (mp.count(P{-x.first.second, x.first.first})) {
      modint s = 2;
      s = s.pow(x.second);
      modint t = 2;
      t = t.pow(mp[P{-x.first.second, x.first.first}]);
      ans *= (s + t - 1);
      cnt -= x.second + mp[P{-x.first.second, x.first.first}];
    }
  }
  assert(cnt < 0);
  modint x = 2;
  x = x.pow(cnt);
  ans *= x;
  x = 2;
  x = x.pow(z);
  modint y = 2;
  y = y.pow(z2);
  ans *= (x + y - 1);
  ans -= 1; // 何も選ばないはなし
  cout << ans << endl;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(15);
  solve();
  return 0;
}