Language: C++

// template version 1.12
using namespace std;
#include <iostream>
#include <bits/stdc++.h>

// varibable settings
#define infile "../test/sample-1.in"
#define int long long //{{{
const int INF=1e18;
const int MOD=1e9+7; //}}}

// define basic macro {{{
#define _overload3(_1,_2,_3,name,...) name
#define _rep(i,n) repi(i,0,n)
#define repi(i,a,b) for(int i=(int)(a);i<(int)(b);++i)
#define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__)
#define _rrep(i,n) rrepi(i,0,n)
#define rrepi(i,a,b) for(int i=(int)((b)-1);i>=(int)(a);--i)
#define rrep(...) _overload3(__VA_ARGS__,rrepi,_rrep,)(__VA_ARGS__)
#define each(i,a) for (auto&& i : a)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define uni(x) sort(all(x));x.erase(unique(all(x)),x.end())
#define ub upper_bound
#define lb lower_bound
#define posl(A, x) (lower_bound(all(A), x)-A.begin())
#define posu(A, x) (upper_bound(all(A),x)-A.begin())
template<class T> inline void chmax(T &a, const T &b) { if((a) < (b)) (a) = (b); }
template<class T> inline void chmin(T &a, const T &b) { if((a) > (b)) (a) = (b); }

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef long double ld;
typedef pair<int,int> pii;
typedef tuple<int,int,int> iii;

template<typename T> using PQ = priority_queue<T, vector<T>, greater<T>>;
struct Fast { Fast(){ std::cin.tie(0); ios::sync_with_stdio(false); } } fast;

#if defined(PCM) || defined(LOCAL)
  #include "lib/dump.hpp"
#else
  #define dump(...) 42
  #define dump_1d(...) 42
  #define dump_2d(...) 42
#endif
//}}}

int dp[1001][1001];

int solve(){
  int n,m;cin>>n>>m;
  vector<int> s(n+1, -1);
  vector<int> t(m+1, -1);
  rep(i,n) cin>>s[i+1];
  rep(i,m) cin>>t[i+1];
  dump(s,t);

  dp[0][0] = 1;

  // vector<vector<map<int, int>>> sa(n, vector<map<int, int>>(m, map<int, int>()));
  // vector<vector<map<int, int>>> ta(n, vector<map<int, int>>(m, map<int, int>()));
  vector<map<int, int>> sa;
  vector<map<int, int>> ta;

  vector<int> cnt;
  rep(i, 1, n+1){
    rep(j, 1, m+1){
      if (j==1){
        sa = vector<map<int, int>>(n, map<int, int>);
      }

      dp[i][j] += dp[i-1][j-1];
      dp[i][j] %= MOD;
      if (s[i]==t[j]){
        dp[i][j] += dp[i-1][j-1];
        dp[i][j] %= MOD;
      }
      dp[i][j] += ta[j][t[i]];
      dp[i][j] %= MOD;
      dp[i][j] += sa[i][t[j]];
      dp[i][j] %= MOD;
    }

    sa[j][s[i]] += dp[i-1][j];
    ta[i][t[j]] += dp[j-1][i];
    sa[j][s[i]] %= MOD;
    ta[i][t[j]] %= MOD;
  }
  cout << sa[n][m] << endl;

  return 0;
}

signed main() { //{{{
#ifdef INPUT_FROM_FILE
  std::ifstream in(infile);
  std::cin.rdbuf(in.rdbuf());
#endif
  solve();
  return 0;
} //}}}


Compiler output:
a.cc: In function 'long long int solve()':
a.cc:73:35: error: expected primary-expression before '(' token
   73 |         sa = vector<map<int, int>>(n, map<int, int>);
      |                                   ^
a.cc:73:52: error: expected primary-expression before ')' token
   73 |         sa = vector<map<int, int>>(n, map<int, int>);
      |                                                    ^
a.cc:88:8: error: 'j' was not declared in this scope
   88 |     sa[j][s[i]] += dp[i-1][j];
      |        ^