Problem p00602 (C++) — buggy submission, verdict: Runtime Error

#include <algorithm>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <vector>
using namespace std;

#define Rep(b, e, i) for (int i = b; i <= e; i++)
#define Repr(e, b, i) for (int i = e; i >= b; i--)
#define rep(n, i) Rep(0, n - 1, i)
#define repr(n, i) Repr(n - 1, 0, i)
#define all(v) (v).begin(), (v).end()
#define pb(v) push_back(v)
#define uniq(v) (v).erase(unique(all(v)), (v).end())
#define bitcnt(x) __builtin_popcount(x)
#define fst first
#define snd second
#define Pqaz(T) priority_queue<T, vector<T>, greater<T>>
#define Pqza(T) priority_queue<T>
#define ENJYU                                                                  \\
  std::ios::sync_with_stdio(false);                                            \\
  std::cin.tie(0);

typedef long long ll;
typedef pair<ll, ll> llP;
typedef pair<int, int> intP;

// vector の中身を出力
template <class T> ostream &operator<<(ostream &o, const vector<T> &v) {
  o << "{";
  for (int i = 0; i < (int)v.size(); i++)
    o << (i > 0 ? ", " : "") << v[i];
  o << "}";
  return o;
}

const int MAX = 2000;
const int MOD = 1001;

struct UnionFind {
  // number of parents(par[i] = i => root)
  vector<int> par;
  // rank of tree
  vector<int> rank;

  UnionFind(int n) : par(n), rank(n, 1) {
    // initialize
    rep(n, i) par[i] = i;
  }

  // find root (keiroasshuku at the same time)
  int root(int x) {
    if (par[x] == x)
      return x;
    else
      return par[x] = root(par[x]);
  }

  // unite
  void unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x == y)
      return;
    if (rank[x] > rank[y])
      swap(x, y);
    par[x] = y;
    if (rank[x] == rank[y])
      rank[y]++;
  }

  // same tree?
  bool same(int x, int y) { return root(x) == root(y); }
};

int f[MAX];

void solve(void) {
  int V, d;

  f[0] = 1, f[1] = 2;
  rep(MOD, i) f[i + 2] = (f[i] + f[i + 1]) % MOD;

  while (cin >> V >> d) {
    UnionFind uf(V);
    rep(V, i) {
      Rep(i + 1, V - 1, j) {
        if (abs(f[i + 1] - f[j + 1]) < d)
          uf.unite(i, j);
      }
    }
    set<int> s;
    rep(V, i) s.insert(uf.root(i));
    cout << s.size() << endl;
  }
}

int main(void) {
  solve();
  // cout << "yui(*-v・)yui" << endl;
  return 0;
}


Error: 0

Fixed submission:

#include <algorithm>
#include <bitset>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <vector>
using namespace std;

#define Rep(b, e, i) for (int i = b; i <= e; i++)
#define Repr(e, b, i) for (int i = e; i >= b; i--)
#define rep(n, i) Rep(0, n - 1, i)
#define repr(n, i) Repr(n - 1, 0, i)
#define all(v) (v).begin(), (v).end()
#define pb(v) push_back(v)
#define uniq(v) (v).erase(unique(all(v)), (v).end())
#define bitcnt(x) __builtin_popcount(x)
#define fst first
#define snd second
#define Pqaz(T) priority_queue<T, vector<T>, greater<T>>
#define Pqza(T) priority_queue<T>
#define ENJYU                                                                  \\
  std::ios::sync_with_stdio(false);                                            \\
  std::cin.tie(0);

typedef long long ll;
typedef pair<ll, ll> llP;
typedef pair<int, int> intP;

// vector の中身を出力
template <class T> ostream &operator<<(ostream &o, const vector<T> &v) {
  o << "{";
  for (int i = 0; i < (int)v.size(); i++)
    o << (i > 0 ? ", " : "") << v[i];
  o << "}";
  return o;
}

const int MAX = 2000;
const int MOD = 1001;

struct UnionFind {
  // number of parents(par[i] = i => root)
  vector<int> par;
  // rank of tree
  vector<int> rank;

  UnionFind(int n) : par(n), rank(n, 1) {
    // initialize
    rep(n, i) par[i] = i;
  }

  // find root (keiroasshuku at the same time)
  int root(int x) {
    if (par[x] == x)
      return x;
    else
      return par[x] = root(par[x]);
  }

  // unite
  void unite(int x, int y) {
    x = root(x);
    y = root(y);
    if (x == y)
      return;
    if (rank[x] > rank[y])
      swap(x, y);
    par[x] = y;
    if (rank[x] == rank[y])
      rank[y]++;
  }

  // same tree?
  bool same(int x, int y) { return root(x) == root(y); }
};

int f[MAX];

void solve(void) {
  int V, d;

  f[0] = 1, f[1] = 2;
  rep(MOD, i) f[i + 2] = (f[i] + f[i + 1]) % MOD;

  while (cin >> V >> d) {
    UnionFind uf(V);
    Rep(1, V, i) {
      int j = i;
      while (abs(f[j] - f[j + 1]) < d) {
        uf.unite(j - 1, j);
        j++;
      }
    }
    set<int> s;
    Rep(1, V, i) s.insert(uf.root(i - 1));
    cout << s.size() << endl;
  }
}

int main(void) {
  solve();
  // cout << "yui(*-v・)yui" << endl;
  return 0;
}