Problem p02558 (C++)

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

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

#define fo(i, n) for (int i = 0; i < n; i++)
#define nl "\n"
#define ff first
#define ss second
#define int long long
#define pb push_back
#define mp make_pair
#define vec(x) vector<x>
#define matrix(x) vector<vector<x>>
#define sz(x) (int)x.size()
#define mem(a, b) memset(a, b, sizeof a)
#define vii vector<pair<int, int>>
#define pii pair<int, int>
#define vi vector<int>
#define mii map<int, int>
#define uii unordered_map<int, int, custom_hash>
#define pqb priority_queue<int>
#define pqs priority_queue<int, vi, greater<int>>
#define gcd(a, b) __gcd(a, b)
#define lcm(a, b) (a * (b / gcd(a, b)))
#define setbits(x) __builtin_popcountll(x)
#define zrobits(x) __builtin_ctzll(x)
#define mod 1000000007
#define MOD 998244353
#define inf 1e18
#define ps(x, y) fixed << setprecision(y) << x
#define mk(arr, n, type) type *arr = new type[n];
#define w(x)                                                                   \
  int x;                                                                       \
  cin >> x;                                                                    \
  while (x--)
#define all(v) v.begin(), v.end()
#define rep(i, begin, end)                                                     \
  for (__typeof(end) i = (begin) - ((begin) > (end));                          \
       i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define len(s) s.length()

#define watch(x) cout << #x << " = " << x << endl

#define deb(...) cerr << "[" << #__VA_ARGS__ << "] : [", DBG(__VA_ARGS__)
void DBG() { cerr << "]\n"; }
template <typename T, typename... Args> void DBG(T first, Args... args) {
  cerr << first;
  if (sizeof...(args))
    cerr << ", ";
  DBG(args...);
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    pbds; // for storing unique elements
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set; // for repeating elements

int power(int a, int b, int m = mod) {
  int ans = 1;
  while (b > 0) {
    if (b & 1)
      ans = (ans * a) % m;
    a = (a * a) % m;
    b >>= 1;
  }
  return ans;
}

void babuBhaiya() {
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}

struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }

  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

const int N = 1e5 + 1;
const double pi = acos(-1);

/*/-----------------------Modular Arithmetic---------------/*/
inline int add(int x, int y) {
  x += y;
  if (x >= mod)
    return x - mod;
  return x;
}
inline int sub(int x, int y) {
  x -= y;
  if (x < 0)
    return x + mod;
  return x;
}
inline int mul(int x, int y) { return (x * 1ll * y) % mod; }
/*/-----------------------------Code begins----------------------------------/*/

int parent[100005];
int R[100005];

int find(int a) {
  if (parent[a] == a)
    return a;
  return parent[a] = find(parent[a]);
}

void merge(int a, int b) {
  a = find(a);
  b = find(b);

  if (a == b)
    return;

  if (R[a] > R[b]) {
    parent[b] = a;
    R[a] += R[b];
  } else {
    parent[a] = b;
    R[b] += R[a];
  }
}

void init_par(int n) {
  fo(i, n) {
    R[i] = 1;
    parent[i] = i;
  }
}

void solve() {

  int n, q;
  cin >> n >> q;
  init_par(n);
  while (q--) {
    int type;
    cin >> type;
    if (type == 0) {
      int a, b;
      cin >> a >> b;
      merge(a, b);
    } else {
      int a, b;
      cin >> a >> b;
      if (find(a) == find(b))
        cout << "1\n";
      else
        cout << "0\n";
    }
  }
}

int32_t main() {
  babuBhaiya();

  int t;

  t = 1;
  // cin>>t;

  while (t--) {
    solve();
  }

  return 0;
}

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

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

#define fo(i, n) for (int i = 0; i < n; i++)
#define nl "\n"
#define ff first
#define ss second
#define int long long
#define pb push_back
#define mp make_pair
#define vec(x) vector<x>
#define matrix(x) vector<vector<x>>
#define sz(x) (int)x.size()
#define mem(a, b) memset(a, b, sizeof a)
#define vii vector<pair<int, int>>
#define pii pair<int, int>
#define vi vector<int>
#define mii map<int, int>
#define uii unordered_map<int, int, custom_hash>
#define pqb priority_queue<int>
#define pqs priority_queue<int, vi, greater<int>>
#define gcd(a, b) __gcd(a, b)
#define lcm(a, b) (a * (b / gcd(a, b)))
#define setbits(x) __builtin_popcountll(x)
#define zrobits(x) __builtin_ctzll(x)
#define mod 1000000007
#define MOD 998244353
#define inf 1e18
#define ps(x, y) fixed << setprecision(y) << x
#define mk(arr, n, type) type *arr = new type[n];
#define w(x)                                                                   \
  int x;                                                                       \
  cin >> x;                                                                    \
  while (x--)
#define all(v) v.begin(), v.end()
#define rep(i, begin, end)                                                     \
  for (__typeof(end) i = (begin) - ((begin) > (end));                          \
       i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define len(s) s.length()

#define watch(x) cout << #x << " = " << x << endl

#define deb(...) cerr << "[" << #__VA_ARGS__ << "] : [", DBG(__VA_ARGS__)
void DBG() { cerr << "]\n"; }
template <typename T, typename... Args> void DBG(T first, Args... args) {
  cerr << first;
  if (sizeof...(args))
    cerr << ", ";
  DBG(args...);
}

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef tree<int, null_type, less<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    pbds; // for storing unique elements
typedef tree<int, null_type, less_equal<int>, rb_tree_tag,
             tree_order_statistics_node_update>
    ordered_set; // for repeating elements

int power(int a, int b, int m = mod) {
  int ans = 1;
  while (b > 0) {
    if (b & 1)
      ans = (ans * a) % m;
    a = (a * a) % m;
    b >>= 1;
  }
  return ans;
}

void babuBhaiya() {
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
  freopen("output.txt", "w", stdout);
#endif
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}

struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }

  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};

const int N = 1e5 + 1;
const double pi = acos(-1);

/*/-----------------------Modular Arithmetic---------------/*/
inline int add(int x, int y) {
  x += y;
  if (x >= mod)
    return x - mod;
  return x;
}
inline int sub(int x, int y) {
  x -= y;
  if (x < 0)
    return x + mod;
  return x;
}
inline int mul(int x, int y) { return (x * 1ll * y) % mod; }
/*/-----------------------------Code begins----------------------------------/*/

int parent[200005];
int R[200005];

int find(int a) {
  if (parent[a] == a)
    return a;
  return parent[a] = find(parent[a]);
}

void merge(int a, int b) {
  a = find(a);
  b = find(b);

  if (a == b)
    return;

  if (R[a] > R[b]) {
    parent[b] = a;
    R[a] += R[b];
  } else {
    parent[a] = b;
    R[b] += R[a];
  }
}

void init_par(int n) {
  fo(i, n) {
    R[i] = 1;
    parent[i] = i;
  }
}

void solve() {

  int n, q;
  cin >> n >> q;
  init_par(n);
  while (q--) {
    int type;
    cin >> type;
    if (type == 0) {
      int a, b;
      cin >> a >> b;
      merge(a, b);
    } else {
      int a, b;
      cin >> a >> b;
      if (find(a) == find(b))
        cout << "1\n";
      else
        cout << "0\n";
    }
  }
}

int32_t main() {
  babuBhaiya();

  int t;

  t = 1;
  // cin>>t;

  while (t--) {
    solve();
  }

  return 0;
}