Problem p02689 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define endl "\n"
typedef long long ll;
const double pi = 3.14159265358979323846;
int ctoi(const char c) {
  if ('0' <= c && c <= '9')
    return (c - '0');
  return -1;
}
vector<int> input(int n) {
  vector<int> vec(n);
  for (int i = 0; i < n; i++) {
    cin >> vec.at(i);
  }
  return vec;
}
void output(vector<int> vec) {
  for (int i = 0; i < vec.size(); i++) {
    cout << vec[i] << " ";
  }
  return;
}
vector<vector<int>> input(int n, int m) {
  vector<vector<int>> table(n, vector<int>(m));
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cin >> table.at(i).at(j);
    }
  }
  return table;
}
void output(vector<vector<int>> table) {
  for (int i = 0; i < table.size(); i++) {
    for (int j = 0; j < table.at(0).size(); j++) {
      cout << table.at(i).at(j) << " ";
    }
    cout << endl;
  }
}
long long perm(int n, int r) {
  if (n < r) {
    cout << "error" << endl;
    return 0;
  }
  long long perm = 1;
  for (int i = n; i > n - r; i--) {
    perm *= i;
  }
  return perm;
}
long long comb(int n, int r) {
  if (n < r) {
    cout << "error" << endl;
    return 0;
  }
  long long comb = perm(n, r);
  for (int i = r; i > 0; i--) {
    comb /= i;
  }
  return comb;
}
long long homo(int n, int r) { return comb(n + r - 1, n - 1); }
long long fact(int n) {
  long long fact = 1;
  for (int i = n; i > 0; i--) {
    fact *= i;
  }
  return fact;
}
int gcd(int a, int b) {
  if (a % b == 0) {
    return (b);
  } else {
    return (gcd(b, a % b));
  }
}
int lcm(int a, int b) { return a * b / gcd(a, b); }
bool isprime(int n) {
  if (n < 2)
    return false;
  else if (n == 2)
    return true;
  else if (n % 2 == 0)
    return false;

  for (int i = 3; i <= sqrt(n); i += 2) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}
vector<long long> divisors(long long N) {
  vector<long long> res;
  for (long long i = 1; i * i <= N; ++i) {
    if (N % i == 0) {
      res.push_back(i);
      // 重複しないならば i の相方である N/i も push
      if (N / i != i)
        res.push_back(N / i);
    }
  }
  // 小さい順に並び替える
  sort(res.begin(), res.end());
  return res;

  /*long long N;
  cin >> N;
  vector<long long> res = divisors(N);
  for (int i = 0; i < res.size(); ++i) {
      cout << res[i] << " ";
  }
  cout << endl;*/
}
vector<pair<long long, long long>> prime_factorize(long long N) {
  vector<pair<long long, long long>> res;
  for (long long a = 2; a * a <= N; ++a) {
    if (N % a != 0)
      continue;
    long long ex = 0;
    while (N % a == 0) {
      ++ex;
      N /= a;
    }
    res.push_back({a, ex});
  }
  if (N != 1)
    res.push_back({N, 1});
  return res;
}
void sayYes(bool f) {
  if (f) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
void sayYES(bool f) {
  if (f) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
}

int main() {
  int n, m;
  cin >> n >> m;
  vector<int> h(n);
  vector<int> ma(n);
  for (int i = 1; i <= n; i++) {
    cin >> h[i];
    ma[i] = 0;
  }

  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    ma[a] = max(ma[a], h[b]);
    ma[b] = max(ma[b], h[a]);
  }
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    if (h[i] > ma[i]) {
      ans++;
    }
  }
  cout << ans << endl;
}

Fixed submission:
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define endl "\n"
typedef long long ll;
const double pi = 3.14159265358979323846;
int ctoi(const char c) {
  if ('0' <= c && c <= '9')
    return (c - '0');
  return -1;
}
vector<int> input(int n) {
  vector<int> vec(n);
  for (int i = 0; i < n; i++) {
    cin >> vec.at(i);
  }
  return vec;
}
void output(vector<int> vec) {
  for (int i = 0; i < vec.size(); i++) {
    cout << vec[i] << " ";
  }
  return;
}
vector<vector<int>> input(int n, int m) {
  vector<vector<int>> table(n, vector<int>(m));
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      cin >> table.at(i).at(j);
    }
  }
  return table;
}
void output(vector<vector<int>> table) {
  for (int i = 0; i < table.size(); i++) {
    for (int j = 0; j < table.at(0).size(); j++) {
      cout << table.at(i).at(j) << " ";
    }
    cout << endl;
  }
}
long long perm(int n, int r) {
  if (n < r) {
    cout << "error" << endl;
    return 0;
  }
  long long perm = 1;
  for (int i = n; i > n - r; i--) {
    perm *= i;
  }
  return perm;
}
long long comb(int n, int r) {
  if (n < r) {
    cout << "error" << endl;
    return 0;
  }
  long long comb = perm(n, r);
  for (int i = r; i > 0; i--) {
    comb /= i;
  }
  return comb;
}
long long homo(int n, int r) { return comb(n + r - 1, n - 1); }
long long fact(int n) {
  long long fact = 1;
  for (int i = n; i > 0; i--) {
    fact *= i;
  }
  return fact;
}
int gcd(int a, int b) {
  if (a % b == 0) {
    return (b);
  } else {
    return (gcd(b, a % b));
  }
}
int lcm(int a, int b) { return a * b / gcd(a, b); }
bool isprime(int n) {
  if (n < 2)
    return false;
  else if (n == 2)
    return true;
  else if (n % 2 == 0)
    return false;

  for (int i = 3; i <= sqrt(n); i += 2) {
    if (n % i == 0) {
      return false;
    }
  }
  return true;
}
vector<long long> divisors(long long N) {
  vector<long long> res;
  for (long long i = 1; i * i <= N; ++i) {
    if (N % i == 0) {
      res.push_back(i);
      // 重複しないならば i の相方である N/i も push
      if (N / i != i)
        res.push_back(N / i);
    }
  }
  // 小さい順に並び替える
  sort(res.begin(), res.end());
  return res;

  /*long long N;
  cin >> N;
  vector<long long> res = divisors(N);
  for (int i = 0; i < res.size(); ++i) {
      cout << res[i] << " ";
  }
  cout << endl;*/
}
vector<pair<long long, long long>> prime_factorize(long long N) {
  vector<pair<long long, long long>> res;
  for (long long a = 2; a * a <= N; ++a) {
    if (N % a != 0)
      continue;
    long long ex = 0;
    while (N % a == 0) {
      ++ex;
      N /= a;
    }
    res.push_back({a, ex});
  }
  if (N != 1)
    res.push_back({N, 1});
  return res;
}
void sayYes(bool f) {
  if (f) {
    cout << "Yes" << endl;
  } else {
    cout << "No" << endl;
  }
}
void sayYES(bool f) {
  if (f) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
}

int main() {
  int n, m;
  cin >> n >> m;
  vector<int> h(100010);
  vector<int> ma(100010);
  for (int i = 1; i <= n; i++) {
    cin >> h[i];
    ma[i] = 0;
  }

  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    ma[a] = max(ma[a], h[b]);
    ma[b] = max(ma[b], h[a]);
  }
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    if (h[i] > ma[i]) {
      ans++;
    }
  }
  cout << ans << endl;
}