Problem p02964 (C++)

Buggy submission (status: Runtime Error):
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#define _USE_MATH_DEFINES
#include <complex>
#include <functional>
#include <math.h>
using namespace std;

#define rep(i, x) for (ll i = 0; i < x; i++)
#define repn(i, x) for (ll i = 1; i <= x; i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 998244353;
const ll MAX = 4000001;
const double eps = 1E-18;

ll max(ll a, ll b) {
  if (a > b) {
    return a;
  }
  return b;
}

ll min(ll a, ll b) {
  if (a > b) {
    return b;
  }
  return a;
}

ll gcd(ll a, ll b) {
  if (b == 0) {
    return a;
  }
  if (a < b) {
    return gcd(b, a);
  }
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

struct edge {
  ll ind;
  ll fr;
  ll to;
  ll d;
};

class mint {
  long long x;

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

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

///////////////////////////

int main() {

  ll N, K;
  cin >> N >> K;

  vector<ll> A(N);
  rep(i, N) cin >> A[i];

  vector<ll> nx(N);
  vector<ll> use(300000, -1);

  rep(i, 2 * N) {
    ll x = A[i % N];

    if (use[x] == -1) {
      use[x] = i;
    } else if (use[x] < N) {
      nx[use[x]] = i - use[x];
      use[x] = i;
    }
  }

  // rep(i, N) cout << nx[i] << endl;

  vector<ll> emp;
  ll v = nx[0];
  emp.push_back(-1);
  emp.push_back(nx[0]);

  while ((v + 1) % N != 0) {
    v = v + 1 + nx[(v + 1) % N];
    emp.push_back(v);
  }

  // rep(i, emp.size()) { cout << emp[i] << endl; }

  ll t = (K * N - 1) % (v + 1);

  auto itr = upper_bound(emp.begin(), emp.end(), t);
  ll e = *(--itr);

  // cout << t << e << endl;

  vector<bool> ct(30000, 0);
  stack<ll> st;

  for (ll i = e + 1; i <= t; i++) {
    ll x = A[i % N];

    if (ct[x] == 0) {
      st.push(x);
      ct[x] = 1;
    }

    else {
      while (st.top() != x) {
        ct[st.top()] = 0;
        st.pop();
      }
      ct[x] = 0;
      st.pop();
    }
  }

  vector<ll> rvans;
  while (!st.empty()) {
    rvans.push_back(st.top());
    st.pop();
  }

  reverse(rvans.begin(), rvans.end());

  rep(i, rvans.size()) { cout << rvans[i] << " "; }

  system("PAUSE");
}


Fixed submission:
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#define _USE_MATH_DEFINES
#include <complex>
#include <functional>
#include <math.h>
using namespace std;

#define rep(i, x) for (ll i = 0; i < x; i++)
#define repn(i, x) for (ll i = 1; i <= x; i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 998244353;
const ll MAX = 4000001;
const double eps = 1E-18;

ll max(ll a, ll b) {
  if (a > b) {
    return a;
  }
  return b;
}

ll min(ll a, ll b) {
  if (a > b) {
    return b;
  }
  return a;
}

ll gcd(ll a, ll b) {
  if (b == 0) {
    return a;
  }
  if (a < b) {
    return gcd(b, a);
  }
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

struct edge {
  ll ind;
  ll fr;
  ll to;
  ll d;
};

class mint {
  long long x;

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

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

///////////////////////////

int main() {

  ll N, K;
  cin >> N >> K;

  vector<ll> A(N);
  rep(i, N) cin >> A[i];

  vector<ll> nx(N);
  vector<ll> use(300000, -1);

  rep(i, 2 * N) {
    ll x = A[i % N];

    if (use[x] == -1) {
      use[x] = i;
    } else if (use[x] < N) {
      nx[use[x]] = i - use[x];
      use[x] = i;
    }
  }

  // rep(i, N) cout << nx[i] << endl;

  vector<ll> emp;
  ll v = nx[0];
  emp.push_back(-1);
  emp.push_back(nx[0]);

  while ((v + 1) % N != 0) {
    v = v + 1 + nx[(v + 1) % N];
    emp.push_back(v);
  }

  // rep(i, emp.size()) { cout << emp[i] << endl; }

  ll t = (K * N - 1) % (v + 1);

  auto itr = upper_bound(emp.begin(), emp.end(), t);
  ll e = *(--itr);

  // cout << t << e << endl;

  vector<bool> ct(300000, 0);
  stack<ll> st;

  for (ll i = e + 1; i <= t; i++) {
    ll x = A[i % N];

    if (ct[x] == 0) {
      st.push(x);
      ct[x] = 1;
    }

    else {
      while (st.top() != x) {
        ct[st.top()] = 0;
        st.pop();
      }
      ct[x] = 0;
      st.pop();
    }
  }

  vector<ll> rvans;
  while (!st.empty()) {
    rvans.push_back(st.top());
    st.pop();
  }

  reverse(rvans.begin(), rvans.end());

  rep(i, rvans.size()) { cout << rvans[i] << " "; }

  system("PAUSE");
}