Problem p02641 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
#include <cassert>
#include <numeric>

using namespace std;
typedef long long ll;
typedef long double ld;
using graph = vector<vector<int>>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using qi = queue<int>;
using qpii = queue<pii>;
using pqi = priority_queue<int>;
using pqr = priority_queue<int, vector<int>, greater<int>>;

#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define repd(i, n) for (ll i = n - 1; i >= 0; i--)
#define F(i, a, b) for (ll i = a; i <= (ll)(b); i++)
#define FD(i, a, b) for (ll i = a; i >= (ll)(b); i--)
#define sd(x) sort(x.rbegin(), x.rend())
// xにはvectorなどのコンテナ
#define all(x) x.begin(), x.end()
#define size(x) ((ll)(x).size())
#define ma(x) *max_element(all(x))
#define mi(x) *min_element(all(x))
#define so(x) sort(all(a));

#define INF 1000000000000
#define M 10000007
#define MAXR 100000

#define pb push_back
#define mp make_pair
#define f first
#define s second
#define fi(x, y) find(all(x), y) != x.end()
#define dfi(x, y) find(all(x), y) == x.end()
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline int rt(T a, T b) {
  if (a % b == 0)
    return a / b;
  else
    return a / b + 1;
}

int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
#define bit(n) (1LL << (n))
#define U(v) v.erase(unique(v.begin(), v.end()), v.end());

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

#define fe(x, a) for (auto &(x) : (a))
#define vin(x)                                                                 \
  for (auto &youso_ : (x))                                                     \
  cin >> youso_
#define vout(x)                                                                \
  for (auto &youso_ : (x))                                                     \
  cout << youso_ << " "
#define sco(x) cout << (x) << " "
#define co(x) cout << (x) << endl
#define en cout << endl
#define gl goto la
#define r0 return 0
void CINT() {}
template <class Head, class... Tail> void CINT(Head &&head, Tail &&...tail) {
  cin >> head;
  CINT(move(tail)...);
}

#define vi vector<int>
#define vll vector<ll>
#define vd vector<double>
#define vld vector<ld>
#define vs vector<string>

#define ci(...)                                                                \
  int __VA_ARGS__;                                                             \
  CINT(__VA_ARGS__)
#define cd(...)                                                                \
  double __VA_ARGS__;                                                          \
  CINT(__VA_ARGS__)
#define cld(...)                                                               \
  ld __VA_ARGS__;                                                              \
  CINT(__VA_ARGS__)
#define cll(...)                                                               \
  ll __VA_ARGS__;                                                              \
  CINT(__VA_ARGS__)
#define cs(...)                                                                \
  string __VA_ARGS__;                                                          \
  CINT(__VA_ARGS__)

struct uf {
  vector<int> par; // par[i]:iの親の番号　(例) par[3] = 2 : 3の親が2
  vector<int> rcount;

  uf(int N) : par(N) { // 最初は全てが根であるとして初期化
    for (int i = 0; i < N; i++)
      par[i] = i;
  }

  int root(int x) { // データxが属する木の根を再帰で得る：root(x) = {xの木の根}
    if (par[x] == x)
      return x;
    return par[x] = root(par[x]);
  }

  void unite(int x, int y) { // xとyの木を併合
    int rx = root(x);        // xの根をrx
    int ry = root(y);        // yの根をry
    if (rx == ry)
      return; // xとyの根が同じ(=同じ木にある)時はそのまま
    par[rx] =
        ry; // xとyの根が同じでない(=同じ木にない)時：xの根rxをyの根ryにつける
  }

  bool same(int x, int y) { // 2つのデータx, yが属する木が同じならtrueを返す
    int rx = root(x);
    int ry = root(y);
    return rx == ry;
  }
};
template <int MOD> struct Fp {
  long long val;
  constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
    if (val < 0)
      val += MOD;
  }
  constexpr int getmod() { return MOD; }
  constexpr Fp operator-() const noexcept { return val ? MOD - val : 0; }
  constexpr Fp operator+(const Fp &r) const noexcept { return Fp(*this) += r; }
  constexpr Fp operator-(const Fp &r) const noexcept { return Fp(*this) -= r; }
  constexpr Fp operator*(const Fp &r) const noexcept { return Fp(*this) *= r; }
  constexpr Fp operator/(const Fp &r) const noexcept { return Fp(*this) /= r; }
  constexpr Fp &operator+=(const Fp &r) noexcept {
    val += r.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }
  constexpr Fp &operator-=(const Fp &r) noexcept {
    val -= r.val;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr Fp &operator*=(const Fp &r) noexcept {
    val = val * r.val % MOD;
    return *this;
  }
  constexpr Fp &operator/=(const Fp &r) noexcept {
    long long a = r.val, b = MOD, u = 1, v = 0;
    while (b) {
      long long t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    val = val * u % MOD;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr bool operator==(const Fp &r) const noexcept {
    return this->val == r.val;
  }
  constexpr bool operator!=(const Fp &r) const noexcept {
    return this->val != r.val;
  }
  friend constexpr ostream &operator<<(ostream &os, const Fp<MOD> &x) noexcept {
    return os << x.val;
  }
  friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
    if (n == 0)
      return 1;
    auto t = modpow(a, n / 2);
    t = t * t;
    if (n & 1)
      t = t * a;
    return t;
  }
};
const ll MOD = 1000000007;
using mint = Fp<MOD>;
mint powm(ll a, ll b) {
  mint re = 1;
  rep(i, b) re *= a;
  return re;
}

int main() {
  ci(x, n);
  vector<int> a(n);
  vector<pii> s;
  vin(a);
  F(i, 1, 100) {
    if (dfi(a, i)) {
      s.pb(mp(abs(x - i), i));
    }
  }
  sd(s);
  co(s[size(s) - 1].s);
}


Fixed submission:
#include <bits/stdc++.h>
#include <cassert>
#include <numeric>

using namespace std;
typedef long long ll;
typedef long double ld;
using graph = vector<vector<int>>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using qi = queue<int>;
using qpii = queue<pii>;
using pqi = priority_queue<int>;
using pqr = priority_queue<int, vector<int>, greater<int>>;

#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define repd(i, n) for (ll i = n - 1; i >= 0; i--)
#define F(i, a, b) for (ll i = a; i <= (ll)(b); i++)
#define FD(i, a, b) for (ll i = a; i >= (ll)(b); i--)
#define sd(x) sort(x.rbegin(), x.rend())
// xにはvectorなどのコンテナ
#define all(x) x.begin(), x.end()
#define size(x) ((ll)(x).size())
#define ma(x) *max_element(all(x))
#define mi(x) *min_element(all(x))
#define so(x) sort(all(a));

#define INF 1000000000000
#define M 10000007
#define MAXR 100000

#define pb push_back
#define mp make_pair
#define f first
#define s second
#define fi(x, y) find(all(x), y) != x.end()
#define dfi(x, y) find(all(x), y) == x.end()
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmin(T &a, T b) {
  if (b < a) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline int rt(T a, T b) {
  if (a % b == 0)
    return a / b;
  else
    return a / b + 1;
}

int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};
#define bit(n) (1LL << (n))
#define U(v) v.erase(unique(v.begin(), v.end()), v.end());

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

#define fe(x, a) for (auto &(x) : (a))
#define vin(x)                                                                 \
  for (auto &youso_ : (x))                                                     \
  cin >> youso_
#define vout(x)                                                                \
  for (auto &youso_ : (x))                                                     \
  cout << youso_ << " "
#define sco(x) cout << (x) << " "
#define co(x) cout << (x) << endl
#define en cout << endl
#define gl goto la
#define r0 return 0
void CINT() {}
template <class Head, class... Tail> void CINT(Head &&head, Tail &&...tail) {
  cin >> head;
  CINT(move(tail)...);
}

#define vi vector<int>
#define vll vector<ll>
#define vd vector<double>
#define vld vector<ld>
#define vs vector<string>

#define ci(...)                                                                \
  int __VA_ARGS__;                                                             \
  CINT(__VA_ARGS__)
#define cd(...)                                                                \
  double __VA_ARGS__;                                                          \
  CINT(__VA_ARGS__)
#define cld(...)                                                               \
  ld __VA_ARGS__;                                                              \
  CINT(__VA_ARGS__)
#define cll(...)                                                               \
  ll __VA_ARGS__;                                                              \
  CINT(__VA_ARGS__)
#define cs(...)                                                                \
  string __VA_ARGS__;                                                          \
  CINT(__VA_ARGS__)

struct uf {
  vector<int> par; // par[i]:iの親の番号　(例) par[3] = 2 : 3の親が2
  vector<int> rcount;

  uf(int N) : par(N) { // 最初は全てが根であるとして初期化
    for (int i = 0; i < N; i++)
      par[i] = i;
  }

  int root(int x) { // データxが属する木の根を再帰で得る：root(x) = {xの木の根}
    if (par[x] == x)
      return x;
    return par[x] = root(par[x]);
  }

  void unite(int x, int y) { // xとyの木を併合
    int rx = root(x);        // xの根をrx
    int ry = root(y);        // yの根をry
    if (rx == ry)
      return; // xとyの根が同じ(=同じ木にある)時はそのまま
    par[rx] =
        ry; // xとyの根が同じでない(=同じ木にない)時：xの根rxをyの根ryにつける
  }

  bool same(int x, int y) { // 2つのデータx, yが属する木が同じならtrueを返す
    int rx = root(x);
    int ry = root(y);
    return rx == ry;
  }
};
template <int MOD> struct Fp {
  long long val;
  constexpr Fp(long long v = 0) noexcept : val(v % MOD) {
    if (val < 0)
      val += MOD;
  }
  constexpr int getmod() { return MOD; }
  constexpr Fp operator-() const noexcept { return val ? MOD - val : 0; }
  constexpr Fp operator+(const Fp &r) const noexcept { return Fp(*this) += r; }
  constexpr Fp operator-(const Fp &r) const noexcept { return Fp(*this) -= r; }
  constexpr Fp operator*(const Fp &r) const noexcept { return Fp(*this) *= r; }
  constexpr Fp operator/(const Fp &r) const noexcept { return Fp(*this) /= r; }
  constexpr Fp &operator+=(const Fp &r) noexcept {
    val += r.val;
    if (val >= MOD)
      val -= MOD;
    return *this;
  }
  constexpr Fp &operator-=(const Fp &r) noexcept {
    val -= r.val;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr Fp &operator*=(const Fp &r) noexcept {
    val = val * r.val % MOD;
    return *this;
  }
  constexpr Fp &operator/=(const Fp &r) noexcept {
    long long a = r.val, b = MOD, u = 1, v = 0;
    while (b) {
      long long t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    val = val * u % MOD;
    if (val < 0)
      val += MOD;
    return *this;
  }
  constexpr bool operator==(const Fp &r) const noexcept {
    return this->val == r.val;
  }
  constexpr bool operator!=(const Fp &r) const noexcept {
    return this->val != r.val;
  }
  friend constexpr ostream &operator<<(ostream &os, const Fp<MOD> &x) noexcept {
    return os << x.val;
  }
  friend constexpr Fp<MOD> modpow(const Fp<MOD> &a, long long n) noexcept {
    if (n == 0)
      return 1;
    auto t = modpow(a, n / 2);
    t = t * t;
    if (n & 1)
      t = t * a;
    return t;
  }
};
const ll MOD = 1000000007;
using mint = Fp<MOD>;
mint powm(ll a, ll b) {
  mint re = 1;
  rep(i, b) re *= a;
  return re;
}

int main() {
  ci(x, n);
  vector<int> a(n);
  vector<pii> s;
  vin(a);
  F(i, 0, 200) {
    if (dfi(a, i)) {
      s.pb(mp(abs(x - i), i));
    }
  }
  sd(s);
  co(s[size(s) - 1].s);
}