Problem p02630 (C++)

Buggy submission (status: Runtime Error):
#pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define CFOR(i, str) for (int i = 0; (str)[i] != '\0'; (i)++)
#define FOR(i, s, r) for (ll i = (s); i < (r); i++)
#define SUM(a) accumulate(a.begin(), a.end(), 0)
#define SORT(v) sort(v.begin(), v.end())
#define RSORT(v) sort(v.rbegin(), v.rend())
#define MAX(v) *max_element(v.begin(), v.end())
#define MIN(v) *min_element(v.begin(), v.end())
#define CNT(v, n) count(v.begin(), v.end(), (n))
#define vi vector<int>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define vpii vector<pair<int, int>>
#define vpic vector<pair<int, char>>
#define mp make_pair
#define n_l '\n'
#define P cout <<

// dbg(var)
#define dbg(...)                                                               \
  cerr << "[" << #__VA_ARGS__ << "]: " << to_string(__VA_ARGS__) << n_l;
template <typename T, size_t N> int SIZE(const T (&t)[N]) { return N; }
template <typename T> int SIZE(const T &t) { return t.size(); }
string to_string(const string s, int x1 = 0, int x2 = 1e9) {
  return '"' + ((x1 < s.size()) ? s.substr(x1, x2 - x1 + 1) : "") + '"';
}
string to_string(const char *s) { return to_string((string)s); }
string to_string(const bool b) { return (b ? "true" : "false"); }
string to_string(const char c) { return string({c}); }
template <size_t N>
string to_string(const bitset<N> &b, int x1 = 0, int x2 = 1e9) {
  string t = "";
  for (int __iii__ = min(x1, SIZE(b)), __jjj__ = min(x2, SIZE(b) - 1);
       __iii__ <= __jjj__; ++__iii__) {
    t += b[__iii__] + '0';
  }
  return '"' + t + '"';
}
template <typename A, typename... C>
string to_string(const A(&v), int x1 = 0, int x2 = 1e9, C... coords);
int l_v_l_v_l = 0, t_a_b_s = 0;
template <typename A, typename B> string to_string(const pair<A, B> &p) {
  l_v_l_v_l++;
  string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
  l_v_l_v_l--;
  return res;
}
template <typename A, typename... C>
string to_string(const A(&v), int x1, int x2, C... coords) {
  int rnk = rank<A>::value;
  string tab(t_a_b_s, ' ');
  string res = "";
  bool first = true;
  if (l_v_l_v_l == 0)
    res += n_l;
  res += tab + "[";
  x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v));
  auto l = begin(v);
  advance(l, x1);
  auto r = l;
  advance(r, (x2 - x1) + (x2 < SIZE(v)));
  for (auto e = l; e != r; e = next(e)) {
    if (!first) {
      res += ", ";
    }
    first = false;
    l_v_l_v_l++;
    if (e != l) {
      if (rnk > 1) {
        res += n_l;
        t_a_b_s = l_v_l_v_l;
      };
    } else {
      t_a_b_s = 0;
    }
    res += to_string(*e, coords...);
    l_v_l_v_l--;
  }
  res += "]";
  if (l_v_l_v_l == 0)
    res += n_l;
  return res;
}
void dbgm() { ; }
template <typename Heads, typename... Tails> void dbgm(Heads H, Tails... T) {
  cerr << to_string(H) << " | ";
  dbgm(T...);
}

// dbgm(var1, var2, var3, ...)
#define dbgm(...)                                                              \
  cerr << "[" << #__VA_ARGS__ << "]: ";                                        \
  dbgm(__VA_ARGS__);                                                           \
  cerr << endl
#define rot(s, k)                                                              \
  rotate(s.begin(), s.begin() + s.size() - (k % s.size()),                     \
         s.end()); //+ve = right, -ve = left

ll binpow(ll a, ll b) {
  ll res = 1;
  while (b > 0) {
    if (b & 1)
      res = res * a;
    a = a * a;
    b >>= 1;
  }
  return res;
}

bool isPrime(ll n) {
  if (n <= 1)
    return false;
  if (n <= 3)
    return true;
  if (n % 2 == 0 || n % 3 == 0)
    return false;
  for (ll i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0)
      return false;
  return true;
}
int total(int n) { return int((-1 + sqrt(1 + 8 * n)) / 2); }
const int N = 1e5 + 1;
ll f[5], n, q;
ll sum;
void solve() {
  int num;
  cin >> n;
  FOR(i, 0, n) {
    cin >> num;
    sum += num;
    f[num]++;
  }
  cin >> q;
  FOR(j, 0, q) {
    int i, r;
    cin >> i >> r;
    sum += (r - i) * f[i];
    f[r] += f[i];
    f[i] = 0;
    cout << sum << n_l;
    // dbg(f);
  }
}

int main() {

  ios::sync_with_stdio(0);
  cin.tie(0);

  clock_t start = clock();

  // int t;
  // cin>>t;
  // while(t--)
  solve();

  // // Google KS
  // for(int i = 1; i < t+1; i++) {

  //
  //     cout<<"Case #"<<i<<": "<<solve()<<"\n";
  // }

  clock_t stop = clock();
  double elapsed = (double)10 * (stop - start) / CLOCKS_PER_SEC;
  cerr << setprecision(5) << fixed;
  cerr << "\nProcess finished in: " << elapsed << "ms\n";

  return 0;
}

Fixed submission:
#pragma GCC optimize("Ofast")
// #pragma GCC target("avx,avx2,fma")

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define CFOR(i, str) for (int i = 0; (str)[i] != '\0'; (i)++)
#define FOR(i, s, r) for (ll i = (s); i < (r); i++)
#define SUM(a) accumulate(a.begin(), a.end(), 0)
#define SORT(v) sort(v.begin(), v.end())
#define RSORT(v) sort(v.rbegin(), v.rend())
#define MAX(v) *max_element(v.begin(), v.end())
#define MIN(v) *min_element(v.begin(), v.end())
#define CNT(v, n) count(v.begin(), v.end(), (n))
#define vi vector<int>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define vpii vector<pair<int, int>>
#define vpic vector<pair<int, char>>
#define mp make_pair
#define n_l '\n'
#define P cout <<

// dbg(var)
#define dbg(...)                                                               \
  cerr << "[" << #__VA_ARGS__ << "]: " << to_string(__VA_ARGS__) << n_l;
template <typename T, size_t N> int SIZE(const T (&t)[N]) { return N; }
template <typename T> int SIZE(const T &t) { return t.size(); }
string to_string(const string s, int x1 = 0, int x2 = 1e9) {
  return '"' + ((x1 < s.size()) ? s.substr(x1, x2 - x1 + 1) : "") + '"';
}
string to_string(const char *s) { return to_string((string)s); }
string to_string(const bool b) { return (b ? "true" : "false"); }
string to_string(const char c) { return string({c}); }
template <size_t N>
string to_string(const bitset<N> &b, int x1 = 0, int x2 = 1e9) {
  string t = "";
  for (int __iii__ = min(x1, SIZE(b)), __jjj__ = min(x2, SIZE(b) - 1);
       __iii__ <= __jjj__; ++__iii__) {
    t += b[__iii__] + '0';
  }
  return '"' + t + '"';
}
template <typename A, typename... C>
string to_string(const A(&v), int x1 = 0, int x2 = 1e9, C... coords);
int l_v_l_v_l = 0, t_a_b_s = 0;
template <typename A, typename B> string to_string(const pair<A, B> &p) {
  l_v_l_v_l++;
  string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
  l_v_l_v_l--;
  return res;
}
template <typename A, typename... C>
string to_string(const A(&v), int x1, int x2, C... coords) {
  int rnk = rank<A>::value;
  string tab(t_a_b_s, ' ');
  string res = "";
  bool first = true;
  if (l_v_l_v_l == 0)
    res += n_l;
  res += tab + "[";
  x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v));
  auto l = begin(v);
  advance(l, x1);
  auto r = l;
  advance(r, (x2 - x1) + (x2 < SIZE(v)));
  for (auto e = l; e != r; e = next(e)) {
    if (!first) {
      res += ", ";
    }
    first = false;
    l_v_l_v_l++;
    if (e != l) {
      if (rnk > 1) {
        res += n_l;
        t_a_b_s = l_v_l_v_l;
      };
    } else {
      t_a_b_s = 0;
    }
    res += to_string(*e, coords...);
    l_v_l_v_l--;
  }
  res += "]";
  if (l_v_l_v_l == 0)
    res += n_l;
  return res;
}
void dbgm() { ; }
template <typename Heads, typename... Tails> void dbgm(Heads H, Tails... T) {
  cerr << to_string(H) << " | ";
  dbgm(T...);
}

// dbgm(var1, var2, var3, ...)
#define dbgm(...)                                                              \
  cerr << "[" << #__VA_ARGS__ << "]: ";                                        \
  dbgm(__VA_ARGS__);                                                           \
  cerr << endl
#define rot(s, k)                                                              \
  rotate(s.begin(), s.begin() + s.size() - (k % s.size()),                     \
         s.end()); //+ve = right, -ve = left

ll binpow(ll a, ll b) {
  ll res = 1;
  while (b > 0) {
    if (b & 1)
      res = res * a;
    a = a * a;
    b >>= 1;
  }
  return res;
}

bool isPrime(ll n) {
  if (n <= 1)
    return false;
  if (n <= 3)
    return true;
  if (n % 2 == 0 || n % 3 == 0)
    return false;
  for (ll i = 5; i * i <= n; i = i + 6)
    if (n % i == 0 || n % (i + 2) == 0)
      return false;
  return true;
}
int total(int n) { return int((-1 + sqrt(1 + 8 * n)) / 2); }
const int N = 1e5 + 1;
ll f[N], n, q;
ll sum;
void solve() {
  int num;
  cin >> n;
  FOR(i, 0, n) {
    cin >> num;
    sum += num;
    f[num]++;
  }
  cin >> q;
  FOR(j, 0, q) {
    int i, r;
    cin >> i >> r;
    sum += (r - i) * f[i];
    f[r] += f[i];
    f[i] = 0;
    cout << sum << n_l;
    // dbg(f);
  }
}

int main() {

  ios::sync_with_stdio(0);
  cin.tie(0);

  clock_t start = clock();

  // int t;
  // cin>>t;
  // while(t--)
  solve();

  // // Google KS
  // for(int i = 1; i < t+1; i++) {

  //
  //     cout<<"Case #"<<i<<": "<<solve()<<"\n";
  // }

  clock_t stop = clock();
  double elapsed = (double)10 * (stop - start) / CLOCKS_PER_SEC;
  cerr << setprecision(5) << fixed;
  cerr << "\nProcess finished in: " << elapsed << "ms\n";

  return 0;
}