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

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
#define REP(i, k, n) for (long long i = k; i < (long long)(n); i++)
#define all(a) a.begin(), a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v, k) (lower_bound(all(v), k) - v.begin())
#define ub(v, k) (upper_bound(all(v), k) - v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T, vector<T>, greater<T>>
#define dame(a)                                                                \\
  {                                                                            \\
    out(a);                                                                    \\
    return 0;                                                                  \\
  }
#define decimal cout << fixed << setprecision(15);
#define dupli(a) a.erase(unique(all(a)), a.end())
typedef long long ll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> PP;
typedef tuple<ll, ll, ll, ll> PPP;
typedef multiset<ll> S;
using vi = vector<ll>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;
using vp = vector<P>;
using vvp = vector<vp>;
using vb = vector<bool>;
using vvb = vector<vb>;
const ll inf = 1001001001001001001;
const ll INF = 1001001001;
const ll mod = 1000000007;
const double eps = 1e-10;
template <class T> bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> void out(T a) { cout << a << '\\n'; }
template <class T> void outp(T a) {
  cout << '(' << a.fi << ',' << a.se << ')' << '\\n';
}
template <class T> void outvp(T v) {
  rep(i, v.size()) cout << '(' << v[i].fi << ',' << v[i].se << ')';
  cout << '\\n';
}
template <class T> void outvvp(T v) { rep(i, v.size()) outvp(v[i]); }
template <class T> void outv(T v) {
  rep(i, v.size()) {
    if (i)
      cout << ' ';
    cout << v[i];
  }
  cout << '\\n';
}
template <class T> void outvv(T v) { rep(i, v.size()) outv(v[i]); }
template <class T> bool isin(T x, T l, T r) { return (l) <= (x) && (x) <= (r); }
template <class T> void yesno(T b) {
  if (b)
    out("yes");
  else
    out("no");
}
template <class T> void YesNo(T b) {
  if (b)
    out("Yes");
  else
    out("No");
}
template <class T> void YESNO(T b) {
  if (b)
    out("YES");
  else
    out("NO");
}
template <class T> void noyes(T b) {
  if (b)
    out("no");
  else
    out("yes");
}
template <class T> void NoYes(T b) {
  if (b)
    out("No");
  else
    out("Yes");
}
template <class T> void NOYES(T b) {
  if (b)
    out("NO");
  else
    out("YES");
}
void outs(ll a, ll b) {
  if (a >= inf - 100)
    out(b);
  else
    out(a);
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll modpow(ll a, ll b) {
  a %= mod;
  if (b == 0)
    return 1;
  if (b & 1)
    return a * modpow(a, b - 1) % mod;
  ll k = modpow(a, b / 2);
  return k * k % mod;
}

int main() {
  ll n;
  cin >> n;
  vector<PP> v;
  ll ans = 0, za = 0, zb = 0;
  rep(i, n) {
    ll a, b;
    cin >> a >> b;
    if (b < 0) {
      a *= -1;
      b *= -1;
    }
    if (a == 0 && b == 0)
      ans++;
    else if (a == 0)
      za++;
    else if (b == 0)
      zb++;
    else {
      ll g = gcd(abs(a), abs(b));
      a /= g;
      b /= g;
      if (a > 0 && b > 0)
        v.pb(a, b, 0);
      else
        v.pb(b, -a, 1);
    }
  }
  sort(all(v));
  ll res = (modpow(2, za) + modpow(2, zb) + mod - 1) % mod;
  n = v.size();
  int w = 0;
  while (w < n) {
    vi sum(2);
    int i = w + 1;
    ll x, y, z;
    tie(x, y, z) = v[w];
    sum[z]++;
    while (i < n) {
      ll a, b, c;
      tie(a, b, c) = v[i];
      if (x == a && y == b)
        sum[c]++;
      else
        break;
      i++;
    }
    res *= (modpow(2, sum[0]) + modpow(2, sum[1]) + mod - 1) % mod;
    res %= mod;
    w = i;
  }
  out((res + ans - 1 + mod) % mod);
}

Error: 0

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
#define REP(i, k, n) for (long long i = k; i < (long long)(n); i++)
#define all(a) a.begin(), a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v, k) (lower_bound(all(v), k) - v.begin())
#define ub(v, k) (upper_bound(all(v), k) - v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T, vector<T>, greater<T>>
#define dame(a)                                                                \\
  {                                                                            \\
    out(a);                                                                    \\
    return 0;                                                                  \\
  }
#define decimal cout << fixed << setprecision(15);
#define dupli(a) a.erase(unique(all(a)), a.end())
typedef long long ll;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> PP;
typedef tuple<ll, ll, ll, ll> PPP;
typedef multiset<ll> S;
using vi = vector<ll>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;
using vp = vector<P>;
using vvp = vector<vp>;
using vb = vector<bool>;
using vvb = vector<vb>;
const ll inf = 1001001001001001001;
const ll INF = 1001001001;
const ll mod = 1000000007;
const double eps = 1e-10;
template <class T> bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> void out(T a) { cout << a << '\\n'; }
template <class T> void outp(T a) {
  cout << '(' << a.fi << ',' << a.se << ')' << '\\n';
}
template <class T> void outvp(T v) {
  rep(i, v.size()) cout << '(' << v[i].fi << ',' << v[i].se << ')';
  cout << '\\n';
}
template <class T> void outvvp(T v) { rep(i, v.size()) outvp(v[i]); }
template <class T> void outv(T v) {
  rep(i, v.size()) {
    if (i)
      cout << ' ';
    cout << v[i];
  }
  cout << '\\n';
}
template <class T> void outvv(T v) { rep(i, v.size()) outv(v[i]); }
template <class T> bool isin(T x, T l, T r) { return (l) <= (x) && (x) <= (r); }
template <class T> void yesno(T b) {
  if (b)
    out("yes");
  else
    out("no");
}
template <class T> void YesNo(T b) {
  if (b)
    out("Yes");
  else
    out("No");
}
template <class T> void YESNO(T b) {
  if (b)
    out("YES");
  else
    out("NO");
}
template <class T> void noyes(T b) {
  if (b)
    out("no");
  else
    out("yes");
}
template <class T> void NoYes(T b) {
  if (b)
    out("No");
  else
    out("Yes");
}
template <class T> void NOYES(T b) {
  if (b)
    out("NO");
  else
    out("YES");
}
void outs(ll a, ll b) {
  if (a >= inf - 100)
    out(b);
  else
    out(a);
}
ll gcd(ll a, ll b) {
  if (b == 0)
    return a;
  return gcd(b, a % b);
}
ll modpow(ll a, ll b) {
  a %= mod;
  if (b == 0)
    return 1;
  if (b & 1)
    return a * modpow(a, b - 1) % mod;
  ll k = modpow(a, b / 2);
  return k * k % mod;
}

int main() {
  ll n;
  cin >> n;
  vector<double> v;
  ll ans = 0, za = 0, zb = 0;
  rep(i, n) {
    double a, b;
    cin >> a >> b;
    if (a == 0 && b == 0)
      ans++;
    else if (a == 0)
      za++;
    else if (b == 0)
      zb++;
    else
      v.pb(a / b);
  }
  sort(all(v));
  ll res = 1;
  res *= modpow(2, za) - 1 + modpow(2, zb) - 1 + 1;
  res %= mod;
  n = v.size();
  vb used(n, false);
  int w = 0;
  ll done = 0;
  while (w < n) {
    if (v[w] > 0)
      break;
    ll sum = 0;
    int i = w;
    while (i < n) {
      if (v[i] == v[w])
        sum++;
      else
        break;
      i++;
    }
    int l = lb(v, -(1 / v[w]));
    int r = l;
    while (r < n) {
      if (v[r] != -(1 / v[w]))
        break;
      r++;
    }
    res *= (modpow(2, r - l) - 1) + (modpow(2, sum) - 1) + 1;
    done += r - l;
    res %= mod;
    w = i;
  }
  res *= modpow(2, n - w - done);
  out((res + ans - 1 + mod) % mod);
}