Submission #558159

#	Time	Username	Problem	Language	Result	Execution time	Memory
558159		Sweezy	Boat (APIO16_boat)	C++17	9 / 100	23 ms	13268 KiB

boat

#include <bits/stdc++.h>

using namespace std;
#define int long long

template <typename A, typename B>
string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string& s) {
  return '"' + s + '"';
}

string to_string(const char* s) {
  return to_string((string) s);
}

string to_string(bool b) {
  return (b ? "true" : "false");
}

string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}

template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}

template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}
  
void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

#define all(a) (a).begin(), (a).end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define reps(i, s, n) for (int i = s; i < (n); ++i)
#define pb push_back
#define sz(a) (int) (a.size())

const int mod = 1e9 + 7;

void solve() {
  int n;
  cin >> n;
  vector<int> l(n), r(n), cs;
  rep(i, n) {
    cin >> l[i] >> r[i];
    cs.pb(l[i]);
    cs.pb(r[i] - 1);
    cs.pb(r[i]);
    cs.pb(r[i] + 1);
  }

  sort(all(cs));
  cs.erase(unique(all(cs)), cs.end());
  vector<pair<int, int>> segs;
  rep(i, sz(cs) - 1) {
    segs.emplace_back(cs[i], cs[i + 1] - 1);
  }
  segs.emplace_back(cs.back(), cs.back());

  debug(segs);

  auto add = [&] (int &a, int b) -> void {
    (a += b) %= mod;
  };

  auto mul = [&] (int a, int b) {
    return a * b % mod;
  };

  auto binpow = [&] (int a, int n) {
    int res = 1;
    while (n) {
      if (n % 2) {
        res = mul(res, a);
      }
      a = mul(a, a);
      n /= 2;
    }
    return res;
  };

  auto inv = [&] (int val) {
    return binpow(val, mod - 2);
  };

  vector<int> f(n + 1), rf(n + 1);
  f[0] = rf[0] = 1;
  reps(i, 1, n + 1) {
    f[i] = mul(f[i - 1], i);
    rf[i] = inv(f[i]);
  }

  auto C = [&] (int n, int k) {
    int res = 1;
    reps(i, 1, k + 1) {
      res = mul(res, n - k + i);
    }
    return mul(res, rf[k]);
  };

  auto sub = [&] (int a, int b) {
    a -= b;
    if (a < 0) a += mod;
    return a;
  };

  vector<vector<int>> dp(n, vector<int> (sz(cs)));
  auto p = dp;
  rep(pos, sz(segs)) {
    if (segs[pos].first >= l[0] && segs[pos].second <= r[0]) {
      dp[0][pos] = segs[pos].second - segs[pos].first + 1;
    }
  }
  p[0][0] = dp[0][0];
  reps(i, 1, sz(segs)) {
    p[0][i] = dp[0][i];
    add(p[0][i], p[0][i - 1]);
  }
  reps(i, 1, n) {
    rep(pos, sz(segs)) {
      if (segs[pos].first < l[i] || segs[pos].second > r[i]) continue;
      int len = segs[pos].second - segs[pos].first + 1;
      add(dp[i][pos], len);
      // rep(prev, pos) {
      //   rep(j, i) {
      //     add(dp[i][pos], mul(len, dp[j][prev]));
      //   }
      // }
      if (pos > 0) {
        add(dp[i][pos], mul(len, p[i - 1][pos - 1]));
      }
      debug(i, pos, dp[i]);
      int cur = 0;
      for (int j = i; j >= i; j--) {
        reps(cnt, 2, min(cur + 1, len + 1)) {
          rep(prev, pos) {
            add(dp[i][pos], mul(C(len, cnt), dp[j][prev]));
          }
        }
        if (segs[pos].first >= l[j] && segs[pos].second <= r[j]) {
          cur++;
        }
      }
    }
    p[i][0] = dp[i][0];
    reps(pos, 1, sz(segs)) {
      add(p[i][pos], p[i][pos - 1]);
      add(p[i][pos], dp[i][pos]);
    }
    rep(pos, sz(segs)) {
      add(p[i][pos], p[i - 1][pos]);
    }
  }

  int res = 0;
  reps(i, 0, n) {
    rep(j, sz(segs)) {
      add(res, dp[i][j]);
    }
  }

  cout << res;
}

signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  solve();
  return 0;
}

Compilation message (stderr)

boat.cpp: In function 'void solve()':
boat.cpp:91:20: warning: statement has no effect [-Wunused-value]
   91 | #define debug(...) 42
      |                    ^~
boat.cpp:122:3: note: in expansion of macro 'debug'
  122 |   debug(segs);
      |   ^~~~~
boat.cpp:91:20: warning: statement has no effect [-Wunused-value]
   91 | #define debug(...) 42
      |                    ^~
boat.cpp:194:7: note: in expansion of macro 'debug'
  194 |       debug(i, pos, dp[i]);
      |       ^~~~~
boat.cpp:163:8: warning: variable 'sub' set but not used [-Wunused-but-set-variable]
  163 |   auto sub = [&] (int a, int b) {
      |        ^~~

• Subtask 1: 9 / 9
• Subtask 2: 0 / 22
• Subtask 3: 0 / 27
• Subtask 4: 0 / 42