Problem p02662 (C++)

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

#ifdef LOCAL
#include "debug.h"
#else
#define DEBUG(...)
#endif

template <class T, class Op = multiplies<T>>
constexpr T power(T a, long long n, Op op = Op(), T e = {1}) {
  assert(n >= 0);
  while (n) {
    if (n & 1)
      e = op(e, a);
    if (n >>= 1)
      a = op(a, a);
  }
  return e;
}

template <unsigned M> struct modular {
  using m = modular;
  static constexpr unsigned mod = M;
  unsigned v;
  modular(long long x = 0) : v((x %= mod) < 0 ? x + mod : x) {}
  m operator-() const { return m() -= *this; }
  m &operator+=(m b) {
    if ((int)(v += b.v - mod) < 0)
      v += mod;
    return *this;
  }
  m &operator-=(m b) {
    if ((int)(v -= b.v) < 0)
      v += mod;
    return *this;
  }
  m &operator*=(m b) {
    v = (uint64_t)v * b.v % mod;
    return *this;
  }
  m &operator/=(m b) { return *this *= power(b, mod - 2); }
  friend m operator+(m a, m b) { return a += b; }
  friend m operator-(m a, m b) { return a -= b; }
  friend m operator*(m a, m b) { return a *= b; }
  friend m operator/(m a, m b) { return a /= b; }
  friend bool operator==(m a, m b) { return a.v == b.v; }
};

using mint = modular<998244353>;

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int n, s;
  cin >> n >> s;
  vector<mint> dp(s + 1);
  dp[0] = 1;
  mint res;
  for (int i = 0; i < n; ++i) {
    int a;
    cin >> a;
    vector<mint> ndp(n + 1);
    for (int j = 0; j <= s; ++j) {
      ndp[j] = 2 * dp[j];
    }
    for (int j = s - a; j >= 0; --j) {
      ndp[j + a] += dp[j];
    }
    swap(dp, ndp);
  }
  cout << dp[s].v << '\n';
}


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

#ifdef LOCAL
#include "debug.h"
#else
#define DEBUG(...)
#endif

template <class T, class Op = multiplies<T>>
constexpr T power(T a, long long n, Op op = Op(), T e = {1}) {
  assert(n >= 0);
  while (n) {
    if (n & 1)
      e = op(e, a);
    if (n >>= 1)
      a = op(a, a);
  }
  return e;
}

template <unsigned M> struct modular {
  using m = modular;
  static constexpr unsigned mod = M;
  unsigned v;
  modular(long long x = 0) : v((x %= mod) < 0 ? x + mod : x) {}
  m operator-() const { return m() -= *this; }
  m &operator+=(m b) {
    if ((int)(v += b.v - mod) < 0)
      v += mod;
    return *this;
  }
  m &operator-=(m b) {
    if ((int)(v -= b.v) < 0)
      v += mod;
    return *this;
  }
  m &operator*=(m b) {
    v = (uint64_t)v * b.v % mod;
    return *this;
  }
  m &operator/=(m b) { return *this *= power(b, mod - 2); }
  friend m operator+(m a, m b) { return a += b; }
  friend m operator-(m a, m b) { return a -= b; }
  friend m operator*(m a, m b) { return a *= b; }
  friend m operator/(m a, m b) { return a /= b; }
  friend bool operator==(m a, m b) { return a.v == b.v; }
};

using mint = modular<998244353>;

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int n, s;
  cin >> n >> s;
  vector<mint> dp(s + 1);
  dp[0] = 1;
  mint res;
  for (int i = 0; i < n; ++i) {
    int a;
    cin >> a;
    vector<mint> ndp(s + 1);
    for (int j = 0; j <= s; ++j) {
      ndp[j] = 2 * dp[j];
    }
    for (int j = s - a; j >= 0; --j) {
      ndp[j + a] += dp[j];
    }
    swap(dp, ndp);
  }
  cout << dp[s].v << '\n';
}