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

#include <bits/stdc++.h>
using namespace std;
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
typedef long long ll;
typedef pair<ll, ll> prl;
typedef vector<ll> vcl;
typedef map<ll, ll> mapl;
typedef unordered_map<ll, ll> umap;
#define pb push_back
#define all(v) v.begin(), v.end()
#define rep(i, a, b) for (ll i = a; i <= b; i++)
#define repi(i, a, b) for (int i = a; i <= b; i++)
#define repr(i, a, b) for (ll i = a; i >= b; i--)
#define reps(i, v) for (ll i = 0; i < v.size(); i++)
template <typename T> void chmin(T &a, const T &b) { a = min(a, b); }
template <typename T> void chmax(T &a, const T &b) { a = max(a, b); }
const ll mod = 1e9 + 7;
map<prl, ll> mp;
map<prl, bool> used;

ll powmod(ll px, ll py, ll pmod) {
  if (py == 0)
    return 1;
  if (py % 2 == 0)
    return powmod((px * px) % pmod, py / 2, pmod);
  else
    return (px * powmod(px, py - 1, pmod)) % pmod;
}

// GCD
ll mygcd(ll x, ll y) {
  if (y == 0)
    return x;
  return mygcd(y, x % y);
}

int main() {
  // your code goes here
  ll n, a[200005], b[200005], g, ans = 1, zs = 0;
  prl mm;
  cin >> n;
  rep(i, 1, n) {
    cin >> a[i] >> b[i];
    g = mygcd(abs(a[i]), abs(b[i]));
    if (g != 0)
      a[i] /= g;
    if (g != 0)
      b[i] /= g;
    if (a[i] < 0) {
      a[i] *= -1;
      b[i] *= -1;
    }
    if (a[i] == 0 && b[i] != 0)
      b[i] = -1;
    if (b[i] == 0 && a[i] != 0)
      a[i] = 1;
  }
  rep(i, 1, n) {
    if (a[i] != 0 || b[i] != 0) {
      mp[{a[i], b[i]}]++;
    } else
      zs++;
  }
  used[{0, 0}] = true;
  ans = 1;
  rep(i, 1, n) {
    if (used[{a[i], b[i]}])
      continue;
    if (b[i] >= 0)
      if (used[{b[i], -a[i]}])
        continue;
    if (b[i] < 0)
      if (used[{-b[i], a[i]}])
        continue;
    if (b[i] >= 0) {
      ans = ans *
            (powmod(2, mp[{a[i], b[i]}], mod) +
             powmod(2, mp[{b[i], -a[i]}], mod) - 1 + mod) %
            mod;
      used[{b[i], -a[i]}] = true;
    } else {
      ans = ans *
            (powmod(2, mp[{a[i], b[i]}], mod) +
             powmod(2, mp[{-b[i], a[i]}], mod) - 1 + mod) %
            mod;
      used[{-b[i], a[i]}] = true;
    }
    used[{a[i], b[i]}] = true;
  }
  cout << (ans - 1 + zs + mod) % mod << endl;
  return 0;
}

Error: 0

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
typedef long long ll;
typedef pair<ll, ll> prl;
typedef vector<ll> vcl;
typedef map<ll, ll> mapl;
typedef unordered_map<ll, ll> umap;
#define pb push_back
#define all(v) v.begin(), v.end()
#define rep(i, a, b) for (ll i = a; i <= b; i++)
#define repi(i, a, b) for (int i = a; i <= b; i++)
#define repr(i, a, b) for (ll i = a; i >= b; i--)
#define reps(i, v) for (ll i = 0; i < v.size(); i++)
template <typename T> void chmin(T &a, const T &b) { a = min(a, b); }
template <typename T> void chmax(T &a, const T &b) { a = max(a, b); }
const ll mod = 1e9 + 7;
map<prl, ll> mp;
map<prl, bool> used;

ll powmod(ll px, ll py, ll pmod) {
  if (py == 0)
    return 1;
  if (py % 2 == 0)
    return powmod((px * px) % pmod, py / 2, pmod);
  else
    return (px * powmod(px, py - 1, pmod)) % pmod;
}

// GCD
ll mygcd(ll x, ll y) {
  if (y == 0)
    return x;
  return mygcd(y, x % y);
}

int main() {
  // your code goes here
  ll n, a[200005], b[200005], g, as = 0, bs = 0, dp[200005] = {0}, x, ans = 1,
                                 zs = 0;
  prl mm;
  cin >> n;
  rep(i, 1, n) {
    cin >> a[i] >> b[i];
    g = mygcd(abs(a[i]), abs(b[i]));
    a[i] /= g;
    b[i] /= g;
    if (a[i] < 0) {
      a[i] *= -1;
      b[i] *= -1;
    }
    if (a[i] == 0 && b[i] != 0)
      b[i] = -1;
    if (b[i] == 0 && a[i] != 0)
      a[i] = 1;
  }
  dp[0] = 0;
  rep(i, 1, n) {
    if (a[i] != 0 || b[i] != 0) {
      mp[{a[i], b[i]}]++;
    } else
      zs++;
  }
  used[{0, 0}] = true;
  ans = zs + 1;
  rep(i, 1, n) {
    if (used[{a[i], b[i]}])
      continue;
    if (b[i] >= 0)
      if (used[{b[i], -a[i]}])
        continue;
    if (b[i] < 0)
      if (used[{-b[i], a[i]}])
        continue;
    if (b[i] >= 0) {
      ans = ans *
            (powmod(2, mp[{a[i], b[i]}], mod) +
             powmod(2, mp[{b[i], -a[i]}], mod) - 1 + mod) %
            mod;
      used[{b[i], -a[i]}] = true;
    } else {
      ans = ans *
            (powmod(2, mp[{a[i], b[i]}], mod) +
             powmod(2, mp[{-b[i], a[i]}], mod) - 1 + mod) %
            mod;
      used[{-b[i], a[i]}] = true;
    }
    used[{a[i], b[i]}] = true;
  }
  cout << (ans - 1) % mod << endl;
  return 0;
}