Problem p03174 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <bits/stdc++.h>
// #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
// #include "boost/multiprecision/cpp_int.hpp"
// typedef boost::multiprecision::cpp_int LL;
typedef long double dd;
#define i_7 (ll)(1E9 + 7)
// #define i_7 998244353
#define i_5 i_7 - 2

ll mod(ll a) {
  ll c = a % i_7;
  if (c >= 0)
    return c;
  return c + i_7;
}
typedef pair<ll, ll> l_l;
typedef pair<dd, dd> d_d;
ll inf = (ll)1E16;
#define rep(i, l, r) for (ll i = l; i <= r; i++)
#define pb push_back
ll max(ll a, ll b) {
  if (a < b)
    return b;
  else
    return a;
}
ll min(ll a, ll b) {
  if (a > b)
    return b;
  else
    return a;
}
void Max(ll &pos, ll val) { pos = max(pos, val); } // Max(dp[n],dp[n-1]);
void Min(ll &pos, ll val) { pos = min(pos, val); }
void Add(ll &pos, ll val) { pos = mod(pos + val); }
dd EPS = 1E-9;
#define fastio                                                                 \
  ios::sync_with_stdio(false);                                                 \
  cin.tie(0);                                                                  \
  cout.tie(0);
#define fi first
#define se second
#define endl "\n"
#define SORT(v) sort(v.begin(), v.end())
#define ERASE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define POSL(v, x) (lower_bound(v.begin(), v.end(), x) - v.begin())
#define POSU(v, x) (upper_bound(v.begin(), v.end(), x) - v.begin())
// template<class T>void max(T a,T b){if(a<b)return b;else return a;}
// template<class T>void min(T a,T b){if(a>b)return b;else return a;}
// template<class T>bool Max(T&a, T b){if(a < b){a = b;return 1;}return 0;}
// template<class T>bool Min(T&a, T b){if(a > b){a = b;return 1;}return 0;}

//////////////////////////

int main() {
  fastio ll n;
  cin >> n;
  ll a[n][n];
  rep(i, 0, n - 1) rep(j, 0, n - 1) cin >> a[i][j];
  ll dp[2][1 << n];
  memset(dp, 0, sizeof(dp));
  rep(j, 0, n - 1) {
    if (a[0][j] == 1)
      dp[0][1 << j] = 1;
  }
  rep(i, 1, n - 1) {
    rep(j, 0, (1 << n) - 1) {
      rep(op, 0, n - 1) {
        if (a[i][op] == 0)
          continue;
        if ((j & (1 << op)) == 0)
          continue;
        Add(dp[i & 1][j], dp[(i - 1) & 1][j - (1 << op)]);
      }
    }
  }
  cout << dp[(n - 1) & 1][(1 << n) - 1] << endl;

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
// #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
// #include "boost/multiprecision/cpp_int.hpp"
// typedef boost::multiprecision::cpp_int LL;
typedef long double dd;
#define i_7 (ll)(1E9 + 7)
// #define i_7 998244353
#define i_5 i_7 - 2

ll mod(ll a) {
  ll c = a % i_7;
  if (c >= 0)
    return c;
  return c + i_7;
}
typedef pair<ll, ll> l_l;
typedef pair<dd, dd> d_d;
ll inf = (ll)1E16;
#define rep(i, l, r) for (ll i = l; i <= r; i++)
#define pb push_back
ll max(ll a, ll b) {
  if (a < b)
    return b;
  else
    return a;
}
ll min(ll a, ll b) {
  if (a > b)
    return b;
  else
    return a;
}
void Max(ll &pos, ll val) { pos = max(pos, val); } // Max(dp[n],dp[n-1]);
void Min(ll &pos, ll val) { pos = min(pos, val); }
void Add(ll &pos, ll val) { pos = mod(pos + val); }
dd EPS = 1E-9;
#define fastio                                                                 \
  ios::sync_with_stdio(false);                                                 \
  cin.tie(0);                                                                  \
  cout.tie(0);
#define fi first
#define se second
#define endl "\n"
#define SORT(v) sort(v.begin(), v.end())
#define ERASE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define POSL(v, x) (lower_bound(v.begin(), v.end(), x) - v.begin())
#define POSU(v, x) (upper_bound(v.begin(), v.end(), x) - v.begin())
// template<class T>void max(T a,T b){if(a<b)return b;else return a;}
// template<class T>void min(T a,T b){if(a>b)return b;else return a;}
// template<class T>bool Max(T&a, T b){if(a < b){a = b;return 1;}return 0;}
// template<class T>bool Min(T&a, T b){if(a > b){a = b;return 1;}return 0;}

//////////////////////////

int main() {
  fastio ll n;
  cin >> n;
  ll a[n][n];
  rep(i, 0, n - 1) rep(j, 0, n - 1) cin >> a[i][j];
  ll dp[2][1 << n];
  memset(dp, 0, sizeof(dp));
  rep(j, 0, n - 1) {
    if (a[0][j] == 1)
      dp[0][1 << j] = 1;
  }
  rep(i, 1, n - 1) {
    rep(j, 0, (1 << n) - 1) {
      ll cnt = 0;
      rep(k, 0, n - 1) if ((j & (1 << k))) cnt++;
      if (cnt != i + 1)
        continue;
      rep(op, 0, n - 1) {
        if (a[i][op] == 0)
          continue;
        if ((j & (1 << op)) == 0)
          continue;
        Add(dp[i & 1][j], dp[(i - 1) & 1][j - (1 << op)]);
      }
    }
  }
  cout << dp[(n - 1) & 1][(1 << n) - 1] << endl;

  return 0;
}