Problem p03688 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;

#define REP(i, s) for (int i = 0; i < s; ++i)
#define ALL(v) (v).begin(), (v).end()
#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define EACH(i, s)                                                             \
  for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)
#define DEBUG
#define int long long
#define INF 1e18
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T1, class T2> ostream &operator<<(ostream &s, pair<T1, T2> P) {
  return s << '<' << P.first << ", " << P.second << '>';
}
template <class T> ostream &operator<<(ostream &s, vector<T> P) {
  for (int i = 0; i < P.size(); ++i) {
    if (i > 0) {
      s << " ";
    }
    s << P[i];
  }
  return s;
}
template <class T> ostream &operator<<(ostream &s, vector<vector<T>> P) {
  for (int i = 0; i < P.size(); ++i) {
    s << endl << P[i];
  }
  return s << endl;
}
template <class T> ostream &operator<<(ostream &s, set<T> P) {
  EACH(it, P) { s << "<" << *it << "> "; }
  return s << endl;
}
template <class T1, class T2> ostream &operator<<(ostream &s, map<T1, T2> P) {
  EACH(it, P) { s << "<" << it->first << "->" << it->second << "> "; }
  return s << endl;
}
template <class T> void show(vector<T> v) {
  for (int i = 0; i < v.size(); i++) {
    cerr << v[i] << " ";
  }
  cerr << "\n";
}
typedef long long ll;

signed main() {
  int n;
  cin >> n;
  vector<int> a(n);
  REP(i, n) { cin >> a[i]; }
  sort(a.begin(), a.end());
  if (a.back() - a[0] >= 2) {
    cout << "No" << endl;
    return 0;
  }
  if (a.back() == a[0]) {
    if (a.back() == 2 || a.back() == 1) {
      cout << "Yes" << endl;
    } else {
      if (n == a[0] + 1 || n >= 2 * a[0]) {
        cout << "Yes" << endl;
      } else {
        cout << "No" << endl;
      }
    }
  } else if (a.back() - a[0] == 1) {
    int idx;
    for (int i = 0; i < n; i++) {
      if (a[i] != a[0]) {
        idx = i;
        break;
      }
    }
    // cerr << idx << endl;
    if (idx == a[0] && a[n - 1] == a[n - 2]) {
      cout << "Yes" << endl;
    } else {
      assert(idx < a[0]);
      cout << "No" << endl;
    }
  }

  return 0;
}

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

#define REP(i, s) for (int i = 0; i < s; ++i)
#define ALL(v) (v).begin(), (v).end()
#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
#define EACH(i, s)                                                             \
  for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)
#define DEBUG
#define int long long
#define INF 1e18
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T1, class T2> ostream &operator<<(ostream &s, pair<T1, T2> P) {
  return s << '<' << P.first << ", " << P.second << '>';
}
template <class T> ostream &operator<<(ostream &s, vector<T> P) {
  for (int i = 0; i < P.size(); ++i) {
    if (i > 0) {
      s << " ";
    }
    s << P[i];
  }
  return s;
}
template <class T> ostream &operator<<(ostream &s, vector<vector<T>> P) {
  for (int i = 0; i < P.size(); ++i) {
    s << endl << P[i];
  }
  return s << endl;
}
template <class T> ostream &operator<<(ostream &s, set<T> P) {
  EACH(it, P) { s << "<" << *it << "> "; }
  return s << endl;
}
template <class T1, class T2> ostream &operator<<(ostream &s, map<T1, T2> P) {
  EACH(it, P) { s << "<" << it->first << "->" << it->second << "> "; }
  return s << endl;
}
template <class T> void show(vector<T> v) {
  for (int i = 0; i < v.size(); i++) {
    cerr << v[i] << " ";
  }
  cerr << "\n";
}
typedef long long ll;

signed main() {
  int n;
  cin >> n;
  vector<int> a(n);
  REP(i, n) { cin >> a[i]; }
  sort(a.begin(), a.end());
  if (a.back() - a[0] >= 2) {
    cout << "No" << endl;
    return 0;
  }
  if (a.back() == a[0]) {
    if (a.back() == 2 || a.back() == 1) {
      cout << "Yes" << endl;
    } else {
      if (n == a[0] + 1 || n >= 2 * a[0]) {
        cout << "Yes" << endl;
      } else {
        cout << "No" << endl;
      }
    }
  } else if (a.back() - a[0] == 1) {
    int idx;
    for (int i = 0; i < n; i++) {
      if (a[i] != a[0]) {
        idx = i;
        break;
      }
    }
    // cerr << idx << endl;
    if (idx == a[0] && a[n - 1] == a[n - 2]) {
      cout << "Yes" << endl;
    } else {
      if (n - idx >= 2 * (a.back() - idx) && idx < a[0]) {
        cout << "Yes" << endl;
      } else
        cout << "No" << endl;
    }
  }

  return 0;
}