Problem p03096 (C++)

Buggy submission (status: Runtime Error):
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// #include<ext/pb_ds/tag_and_trait.hpp>
// using namespace __gnu_pbds;
// #include<boost/multiprecision/cpp_int.hpp>
// namespace multiprecisioninteger = boost::multiprecision;
// using cint=multiprecisioninteger::cpp_int;
using namespace std;
using ll = long long;
#define double long double
using datas = pair<ll, ll>;
using ddatas = pair<double, double>;
using tdata = pair<ll, datas>;
using vec = vector<ll>;
using mat = vector<vec>;
using pvec = vector<datas>;
using pmat = vector<pvec>;
// using
// llset=tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>;
#define For(i, a, b) for (i = a; i < (ll)b; ++i)
#define bFor(i, b, a) for (i = b, --i; i >= (ll)a; --i)
#define rep(i, N) For(i, 0, N)
#define rep1(i, N) For(i, 1, N)
#define brep(i, N) bFor(i, N, 0)
#define brep1(i, N) bFor(i, N, 1)
#define all(v) (v).begin(), (v).end()
#define allr(v) (v).rbegin(), (v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define endl "\n"
#define eb emplace_back
#define print(v) cout << v << endl
#define printyes cout << "Yes" << endl
#define printno cout << "No" << endl
#define printYES cout << "YES" << endl
#define printNO cout << "NO" << endl
#define output(v)                                                              \
  do {                                                                         \
    bool f = 0;                                                                \
    for (auto outi : v) {                                                      \
      cout << (f ? " " : "") << outi;                                          \
      f = 1;                                                                   \
    }                                                                          \
    cout << endl;                                                              \
  } while (0)
#define matoutput(v)                                                           \
  do {                                                                         \
    for (auto outimat : v)                                                     \
      output(outimat);                                                         \
  } while (0)
const ll mod = 1000000007;
// const ll mod=998244353;
const ll inf = 1LL << 60;
const double PI = acos(-1);
const double eps = 1e-9;
template <class T> inline bool chmax(T &a, T b) {
  bool x = a < b;
  if (x)
    a = b;
  return x;
}
template <class T> inline bool chmin(T &a, T b) {
  bool x = a > b;
  if (x)
    a = b;
  return x;
}

void startupcpp() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}

ll gcd(ll a, ll b) {
  if (!b)
    return abs(a);
  return (a % b == 0) ? abs(b) : gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

int main() {
  startupcpp();
  int i, N, x;
  cin >> N;
  vec c(1e5 + 1, -1), ans(N, 0);
  rep(i, N) {
    cin >> x;
    if (i)
      ans[i] = ans[i - 1];
    else
      ans[i] = 1;
    if (c[x] != -1 && c[x] != i - 1) {
      (ans[i] += ans[c[x]]) %= mod;
    }
    c[x] = i;
  }
  print(ans[N - 1]);
}

Fixed submission:
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
// #include<ext/pb_ds/assoc_container.hpp>
// #include<ext/pb_ds/tree_policy.hpp>
// #include<ext/pb_ds/tag_and_trait.hpp>
// using namespace __gnu_pbds;
// #include<boost/multiprecision/cpp_int.hpp>
// namespace multiprecisioninteger = boost::multiprecision;
// using cint=multiprecisioninteger::cpp_int;
using namespace std;
using ll = long long;
#define double long double
using datas = pair<ll, ll>;
using ddatas = pair<double, double>;
using tdata = pair<ll, datas>;
using vec = vector<ll>;
using mat = vector<vec>;
using pvec = vector<datas>;
using pmat = vector<pvec>;
// using
// llset=tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>;
#define For(i, a, b) for (i = a; i < (ll)b; ++i)
#define bFor(i, b, a) for (i = b, --i; i >= (ll)a; --i)
#define rep(i, N) For(i, 0, N)
#define rep1(i, N) For(i, 1, N)
#define brep(i, N) bFor(i, N, 0)
#define brep1(i, N) bFor(i, N, 1)
#define all(v) (v).begin(), (v).end()
#define allr(v) (v).rbegin(), (v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define endl "\n"
#define eb emplace_back
#define print(v) cout << v << endl
#define printyes cout << "Yes" << endl
#define printno cout << "No" << endl
#define printYES cout << "YES" << endl
#define printNO cout << "NO" << endl
#define output(v)                                                              \
  do {                                                                         \
    bool f = 0;                                                                \
    for (auto outi : v) {                                                      \
      cout << (f ? " " : "") << outi;                                          \
      f = 1;                                                                   \
    }                                                                          \
    cout << endl;                                                              \
  } while (0)
#define matoutput(v)                                                           \
  do {                                                                         \
    for (auto outimat : v)                                                     \
      output(outimat);                                                         \
  } while (0)
const ll mod = 1000000007;
// const ll mod=998244353;
const ll inf = 1LL << 60;
const double PI = acos(-1);
const double eps = 1e-9;
template <class T> inline bool chmax(T &a, T b) {
  bool x = a < b;
  if (x)
    a = b;
  return x;
}
template <class T> inline bool chmin(T &a, T b) {
  bool x = a > b;
  if (x)
    a = b;
  return x;
}

void startupcpp() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
}

ll gcd(ll a, ll b) {
  if (!b)
    return abs(a);
  return (a % b == 0) ? abs(b) : gcd(b, a % b);
}
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

int main() {
  startupcpp();
  int i, N, x;
  cin >> N;
  vec c(2e5 + 1, -1), ans(N, 0);
  rep(i, N) {
    cin >> x;
    if (i)
      ans[i] = ans[i - 1];
    else
      ans[i] = 1;
    if (c[x] != -1 && c[x] != i - 1) {
      (ans[i] += ans[c[x]]) %= mod;
    }
    c[x] = i;
  }
  print(ans[N - 1]);
}