Problem p04015 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
// type alias
typedef long long LL;
typedef pair<int, int> II;
typedef tuple<int, int, int> III;
typedef vector<int> VI;
typedef vector<string> VS;
typedef unordered_map<int, int> MAPII;
typedef unordered_set<int> SETI;
template <class T> using VV = vector<vector<T>>;
// minmax
template <class T> inline T SMIN(T &a, const T b) {
  return a = (a > b) ? b : a;
}
template <class T> inline T SMAX(T &a, const T b) {
  return a = (a < b) ? b : a;
}
// repetition
#define FORE(i, a, b) for (int i = (a); i <= (b); ++i)
#define REPE(i, n) for (int i = 0; i <= (n); ++i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define FORR(x, arr) for (auto &x : arr)
#define SZ(a) int((a).size())
// collection
#define ALL(c) (c).begin(), (c).end()
// DP
#define MINUS(dp) memset(dp, -1, sizeof(dp))
#define ZERO(dp) memset(dp, 0, sizeof(dp))
// stdout
#define println(args...) fprintf(stdout, ##args), putchar('\n');
// debug cerr
template <class Iter> void __kumaerrc(Iter begin, Iter end) {
  for (; begin != end; ++begin) {
    cerr << *begin << ',';
  }
  cerr << endl;
}
void __kumaerr(istream_iterator<string> it) {
  (void)it;
  cerr << endl;
}
template <typename T, typename... Args>
void __kumaerr(istream_iterator<string> it, T a, Args... args) {
  cerr << *it << "=" << a << ", ", __kumaerr(++it, args...);
}
template <typename S, typename T>
std::ostream &operator<<(std::ostream &_os, const std::pair<S, T> &_p) {
  return _os << "{" << _p.first << ',' << _p.second << "}";
}
#define __KUMATRACE__ true
#ifdef __KUMATRACE__
#define dump(args...)                                                          \
  {                                                                            \
    string _s = #args;                                                         \
    replace(_s.begin(), _s.end(), ',', ' ');                                   \
    stringstream _ss(_s);                                                      \
    istream_iterator<string> _it(_ss);                                         \
    __kumaerr(_it, args);                                                      \
  }
#define dumpc(ar)                                                              \
  {                                                                            \
    cerr << #ar << ": ";                                                       \
    FORR(x, (ar)) { cerr << x << ','; }                                        \
    cerr << endl;                                                              \
  }
#define dumpC(beg, end)                                                        \
  {                                                                            \
    cerr << "~" << #end << ": ";                                               \
    __kumaerrc(beg, end);                                                      \
  }
#else
#define dump(args...)
#define dumpc(ar)
#define dumpC(beg, end)
#endif

// $ cp-batch TakahashiAndCards | diff TakahashiAndCards.out -
// $ g++ -std=c++14 -Wall -O2 -D_GLIBCXX_DEBUG -fsanitize=address
// TakahashiAndCards.cpp && ./a.out

/*

 7/16/2020

 9:03-

 */

const int MAX_N = 50 + 1;
int X[MAX_N];
int N, A;

const int MAX_S = MAX_N * MAX_N;
LL dp[MAX_N][MAX_S];
void solve() {
  dp[0][0] = 1;
  REP(i, N)
  for (int cnt = N; cnt >= 0; --cnt) for (int sum = MAX_S - 1; sum >= 0;
                                          --sum) {
    // if(dp[cnt][sum]>0) dump(i,cnt,sum,dp[cnt][sum]);
    if (sum + X[i] < MAX_S)
      dp[cnt + 1][sum + X[i]] += dp[cnt][sum];
  }
  LL res = 0;
  FORE(cnt, 1, N) {
    res += dp[cnt][cnt * A];
    // if(dp[cnt][cnt*A]>0) dump(cnt,cnt*A,dp[cnt][cnt*A]);
  }
  cout << res << endl;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << setprecision(12) << fixed;

  cin >> N >> A;
  REP(i, N) cin >> X[i];
  solve();

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
// type alias
typedef long long LL;
typedef pair<int, int> II;
typedef tuple<int, int, int> III;
typedef vector<int> VI;
typedef vector<string> VS;
typedef unordered_map<int, int> MAPII;
typedef unordered_set<int> SETI;
template <class T> using VV = vector<vector<T>>;
// minmax
template <class T> inline T SMIN(T &a, const T b) {
  return a = (a > b) ? b : a;
}
template <class T> inline T SMAX(T &a, const T b) {
  return a = (a < b) ? b : a;
}
// repetition
#define FORE(i, a, b) for (int i = (a); i <= (b); ++i)
#define REPE(i, n) for (int i = 0; i <= (n); ++i)
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define FORR(x, arr) for (auto &x : arr)
#define SZ(a) int((a).size())
// collection
#define ALL(c) (c).begin(), (c).end()
// DP
#define MINUS(dp) memset(dp, -1, sizeof(dp))
#define ZERO(dp) memset(dp, 0, sizeof(dp))
// stdout
#define println(args...) fprintf(stdout, ##args), putchar('\n');
// debug cerr
template <class Iter> void __kumaerrc(Iter begin, Iter end) {
  for (; begin != end; ++begin) {
    cerr << *begin << ',';
  }
  cerr << endl;
}
void __kumaerr(istream_iterator<string> it) {
  (void)it;
  cerr << endl;
}
template <typename T, typename... Args>
void __kumaerr(istream_iterator<string> it, T a, Args... args) {
  cerr << *it << "=" << a << ", ", __kumaerr(++it, args...);
}
template <typename S, typename T>
std::ostream &operator<<(std::ostream &_os, const std::pair<S, T> &_p) {
  return _os << "{" << _p.first << ',' << _p.second << "}";
}
#define __KUMATRACE__ true
#ifdef __KUMATRACE__
#define dump(args...)                                                          \
  {                                                                            \
    string _s = #args;                                                         \
    replace(_s.begin(), _s.end(), ',', ' ');                                   \
    stringstream _ss(_s);                                                      \
    istream_iterator<string> _it(_ss);                                         \
    __kumaerr(_it, args);                                                      \
  }
#define dumpc(ar)                                                              \
  {                                                                            \
    cerr << #ar << ": ";                                                       \
    FORR(x, (ar)) { cerr << x << ','; }                                        \
    cerr << endl;                                                              \
  }
#define dumpC(beg, end)                                                        \
  {                                                                            \
    cerr << "~" << #end << ": ";                                               \
    __kumaerrc(beg, end);                                                      \
  }
#else
#define dump(args...)
#define dumpc(ar)
#define dumpC(beg, end)
#endif

// $ cp-batch TakahashiAndCards | diff TakahashiAndCards.out -
// $ g++ -std=c++14 -Wall -O2 -D_GLIBCXX_DEBUG -fsanitize=address
// TakahashiAndCards.cpp && ./a.out

/*

 7/16/2020

 9:03-

 */

const int MAX_N = 50 + 1;
int X[MAX_N];
int N, A;

const int MAX_S = MAX_N * MAX_N;
LL dp[MAX_N][MAX_S];
void solve() {
  dp[0][0] = 1;
  REP(i, N)
  for (int cnt = N - 1; cnt >= 0; --cnt) for (int sum = MAX_S - 1; sum >= 0;
                                              --sum) {
    // if(dp[cnt][sum]>0) dump(i,cnt,sum,dp[cnt][sum]);
    if (sum + X[i] < MAX_S)
      dp[cnt + 1][sum + X[i]] += dp[cnt][sum];
  }
  LL res = 0;
  FORE(cnt, 1, N) {
    res += dp[cnt][cnt * A];
    // if(dp[cnt][cnt*A]>0) dump(cnt,cnt*A,dp[cnt][cnt*A]);
  }
  cout << res << endl;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << setprecision(12) << fixed;

  cin >> N >> A;
  REP(i, N) cin >> X[i];
  solve();

  return 0;
}