Problem p01551 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = int(a); i < int(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)

#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = int(a) - 1; i >= int(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)

#define _all(arg) begin(arg), end(arg)
#define uniq(arg) sort(_all(arg)), (arg).erase(unique(_all(arg)), end(arg))
#define getidx(ary, key) lower_bound(_all(ary), key) - begin(ary)
#define clr(a, b) memset((a), (b), sizeof(a))
#define bit(n) (1LL << (n))
#define popcount(n) (__builtin_popcountll(n))

using namespace std;

template <class T> bool chmax(T &a, const T &b) {
  return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
  return (b < a) ? (a = b, 1) : 0;
}

using ll = long long;
using R = long double;
const R EPS = 1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R &r) { return (r > EPS) - (r < -EPS); }
inline R sq(R x) { return sqrt(max(x, 0.0L)); }

const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};

// Problem Specific Parameter:

vector<int> seq[55];
map<string, int> str2idx;

string bnf[55];
string AGCT = "ATGC";

void func(int i, int n) {
  stringstream ss(bnf[i]);
  string tmp;

  ss >> tmp;
  tmp = tmp.substr(0, tmp.size() - 1);
  str2idx[tmp] = i;

  while (ss >> tmp) {
    if (tmp[0] == '[') {
      tmp = tmp.substr(1, tmp.size() - 2);
      int val = 0;
      for (auto &mark : tmp)
        rep(j, 4) if (mark == AGCT[j]) val |= (1 << j);
      seq[i].push_back(val);
    } else {
      const int idx = str2idx[tmp];
      seq[i].insert(end(seq[i]), begin(seq[idx]), end(seq[idx]));
    }

    if (seq[i].size() > n)
      break;
    if (ss.eof())
      break;
  }
}

const ll mod = 1000000007LL;
ll dp[55][55][55][55];

int main(void) {
  int nATGC[4];
  rep(i, 4) cin >> nATGC[i];
  const int total = accumulate(nATGC, nATGC + 4, 0);

  int m;
  cin >> m;

  cin.ignore();
  rep(i, m) getline(cin, bnf[i]);
  rrep(i, m) func(i, total);

  dp[0][0][0][0] = 1LL;

  if (total != int(seq[0].size())) {
    cout << 0 << endl;
    return 0;
  }

  rep(i, total) rep(na, nATGC[0] + 1) rep(nt, nATGC[1] + 1)
      rep(ng, nATGC[2] + 1) {
    const int nc = i - na - nt - ng;
    if (nc < 0 or nATGC[3] < nc)
      continue;

    dp[na][nt][ng][nc] %= mod;

    if (na < nATGC[0] and seq[0][i] & 1) {
      dp[na + 1][nt][ng][nc] += dp[na][nt][ng][nc];
      dp[na + 1][nt][ng][nc] %= mod;
    }

    if (nt < nATGC[1] and seq[0][i] & 2) {
      dp[na][nt + 1][ng][nc] += dp[na][nt][ng][nc];
      dp[na][nt + 1][ng][nc] %= mod;
    }

    if (ng < nATGC[2] and seq[0][i] & 4) {
      dp[na][nt][ng + 1][nc] += dp[na][nt][ng][nc];
      dp[na][nt][ng + 1][nc] %= mod;
    }

    if (nc < nATGC[3] and seq[0][i] & 8) {
      dp[na][nt][ng][nc + 1] += dp[na][nt][ng][nc];
      dp[na][nt][ng][nc + 1] %= mod;
    }
  }

  cout << dp[nATGC[0]][nATGC[1]][nATGC[2]][nATGC[3]] << endl;

  return 0;
}

Error: 0

Fixed submission:

#include <bits/stdc++.h>

#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = int(a); i < int(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)

#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = int(a) - 1; i >= int(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)

#define _all(arg) begin(arg), end(arg)
#define uniq(arg) sort(_all(arg)), (arg).erase(unique(_all(arg)), end(arg))
#define getidx(ary, key) lower_bound(_all(ary), key) - begin(ary)
#define clr(a, b) memset((a), (b), sizeof(a))
#define bit(n) (1LL << (n))
#define popcount(n) (__builtin_popcountll(n))

using namespace std;

template <class T> bool chmax(T &a, const T &b) {
  return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
  return (b < a) ? (a = b, 1) : 0;
}

using ll = long long;
using R = long double;
const R EPS = 1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R &r) { return (r > EPS) - (r < -EPS); }
inline R sq(R x) { return sqrt(max(x, 0.0L)); }

const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};

// Problem Specific Parameter:

vector<int> seq[55];
map<string, int> str2idx;

string bnf[55];
string AGCT = "ATGC";

void func(int i) {
  stringstream ss(bnf[i]);
  string tmp;

  ss >> tmp;
  tmp = tmp.substr(0, tmp.size() - 1);
  str2idx[tmp] = i;

  while (ss >> tmp) {
    if (tmp[0] == '[') {
      tmp = tmp.substr(1, tmp.size() - 2);
      int val = 0;
      for (auto &mark : tmp)
        rep(j, 4) if (mark == AGCT[j]) val |= (1 << j);
      seq[i].push_back(val);
    } else {
      const int idx = str2idx[tmp];
      seq[i].insert(end(seq[i]), begin(seq[idx]), end(seq[idx]));
    }
    if (ss.eof())
      break;
  }
}

const ll mod = 1000000007LL;
ll dp[55][55][55][55];

int main(void) {
  int nATGC[4];
  rep(i, 4) cin >> nATGC[i];

  int m;
  cin >> m;

  cin.ignore();
  rep(i, m) getline(cin, bnf[i]);
  rrep(i, m) func(i);

  dp[0][0][0][0] = 1LL;
  const int total = accumulate(nATGC, nATGC + 4, 0);

  if (total != int(seq[0].size())) {
    cout << 0 << endl;
    return 0;
  }

  rep(i, total) rep(na, nATGC[0] + 1) rep(nt, nATGC[1] + 1)
      rep(ng, nATGC[2] + 1) {
    const int nc = i - na - nt - ng;
    if (nc < 0 or nATGC[3] < nc)
      continue;

    dp[na][nt][ng][nc] %= mod;

    if (na < nATGC[0] and seq[0][i] & 1)
      dp[na + 1][nt][ng][nc] += dp[na][nt][ng][nc];
    if (nt < nATGC[1] and seq[0][i] & 2)
      dp[na][nt + 1][ng][nc] += dp[na][nt][ng][nc];
    if (ng < nATGC[2] and seq[0][i] & 4)
      dp[na][nt][ng + 1][nc] += dp[na][nt][ng][nc];
    if (nc < nATGC[3] and seq[0][i] & 8)
      dp[na][nt][ng][nc + 1] += dp[na][nt][ng][nc];
  }

  cout << dp[nATGC[0]][nATGC[1]][nATGC[2]][nATGC[3]] << endl;

  return 0;
}