Problem p02689 (C++) — buggy submission, verdict: Runtime Error

// include
//------------------------------------------
#include <algorithm>
#include <bits/stdc++.h>
#include <bitset>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

// conversion
//------------------------------------------
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

// math
//-------------------------------------------
template <class T> inline T sqr(T x) { return x * x; }
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
// typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

// container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i, c)                                                             \\
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define fore(i, a) for (auto &i : a)

// constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);

// clear memory
#define CLR(a) memset((a), 0, sizeof(a))

// debug
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

int main() {
  int N, M;
  cin >> N >> M;
  long long H[N], A[M], B[M];
  for (int i = 0; i < N; ++i) {
    cin >> H[i];
  }
  vector<vector<long long>> v(M + 1000);
  for (int i = 0; i < M; ++i) {
    cin >> A[i] >> B[i];
    A[i] -= 1, B[i] -= 1;
    v[A[i]].push_back(B[i]);
    v[B[i]].push_back(A[i]);
  }
  long long good_count = 0;
  for (long long i = 0; i < N; ++i) {
    bool no_exist = true;
    bool all_exist = true;
    if (v[i].size() >= 1)
      no_exist = false;
    for (long long j = 0; j < v[i].size(); ++j) {
      if (H[i] <= H[v[i][j]]) {
        all_exist = false;
      }
    }
    if (no_exist)
      good_count++;
    else if (all_exist)
      good_count++;
  }
  cout << good_count;
}

Error: WA

Fixed submission:

// include
//------------------------------------------
#include <algorithm>
#include <bits/stdc++.h>
#include <bitset>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

// conversion
//------------------------------------------
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T> inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}

// math
//-------------------------------------------
template <class T> inline T sqr(T x) { return x * x; }
template <class T> bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
// typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

// container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i, c)                                                             \\
  for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define fore(i, a) for (auto &i : a)

// constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);

// clear memory
#define CLR(a) memset((a), 0, sizeof(a))

// debug
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x)                                                               \\
  cerr << #x << " = " << (x) << " (L" << __LINE__ << ")"                       \\
       << " " << __FILE__ << endl;

int main() {
  int N, M;
  cin >> N >> M;
  long long H[N], A[M], B[M];
  for (int i = 0; i < N; ++i) {
    cin >> H[i];
  }
  vector<vector<long long>> v(M + 1);
  for (int i = 0; i < M; ++i) {
    cin >> A[i] >> B[i];
    A[i] -= 1, B[i] -= 1;
    v[A[i]].push_back(B[i]);
    v[B[i]].push_back(A[i]);
  }
  long long good_count = 0;
  for (long long i = 0; i < N; ++i) {
    bool no_exist = true;
    bool all_exist = true;
    if (v[i].size() >= 1)
      no_exist = false;
    for (long long j = 0; j < v[i].size(); ++j) {
      if (H[i] <= H[v[i][j]]) {
        all_exist = false;
      }
    }
    if (no_exist)
      good_count++;
    else if (all_exist)
      good_count++;
  }
  cout << good_count;
}