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Submission #245320

# Submission time Handle Problem Language Result Execution time Memory
245320 2020-07-06T03:54:40 Z neihcr7j Boat (APIO16_boat) C++14
9 / 100
 656 ms 5240 KB 
#include<bits/stdc++.h>

#define M 1000000007
#define maxn 502

using namespace std;
typedef long long ll;

inline ll norm(ll a) {
  return (a < 0 ? a + M : (a >= M ? a - M : a));
}

inline ll mul(ll a, ll b) {
  return a * b % M;
}

ll power(ll a, ll b) {
  if (b == 0) return 1;
  if (b&1) return mul(power(a, b - 1), a);
  ll t = power(a, b / 2);
  return mul(t, t);
}

ll gt[maxn * 2], igt[maxn * 2];

void precalc(){
  int n = 1000;

  gt[0] = 1;
  for (int i = 1; i <= n; ++i)
    gt[i] = mul(gt[i - 1], i);

  igt[n] = power(gt[n], M - 2);

  for (int i = n - 1; i >= 0; --i)
    igt[i] = mul(igt[i + 1], i + 1);
}

ll C(int n, int k) {
  return mul(mul(gt[n], igt[k]), igt[n - k]);
}


int n;

int l[maxn], r[maxn];
vector < pair < int, int > > seg;
vector < vector < int > > a;
vector < int > leng;

ll dp[maxn * 4][maxn];

int main(){
  #define TASK "ABC"
//  freopen(TASK".inp", "r", stdin); freopen(TASK".out", "w", stdout);
  ios_base::sync_with_stdio(0);

  precalc();

  cin >> n;

  vector < int > ret;

  for (int i = 1; i <= n; ++i) {
    cin >> l[i] >> r[i];

    ret.push_back(l[i]);
    ret.push_back(r[i]);
  }

  sort(ret.begin(), ret.end());

  seg.push_back({ret[0], ret[0]});

  for (int i = 1; i < ret.size(); ++i)
    if (ret[i] != ret[i - 1]) {
      if (i == ret.size() || ret[i] != ret[i + 1]) {
        seg.push_back({ret[i - 1] + 1, ret[i]});
        continue;
      }

      if (ret[i - 1] + 1 != ret[i])
        seg.push_back({ret[i - 1] + 1, ret[i] - 1});
      seg.push_back({ret[i], ret[i]});
    }

  a = vector < vector < int > >(seg.size(), vector < int >(0, 0));
  leng = vector < int > (seg.size(), 0);

  for (int i = 0; i < seg.size(); ++i) {
    for (int j = 1; j <= n; ++j)
      if (l[j] <= seg[i].first && seg[i].second <= r[j])
        a[i].push_back(j);
    leng[i] = seg[i].second - seg[i].first + 1;
  }

  ll ans = 0;

  for (int i = 0; i < seg.size(); ++i) {
    ll l = leng[i];

    vector < ll > c(a[i].size() + 1, 0), val(a[i].size() + 1, 0);

    c[0] = 1;

    for (int k = 1; k <= a[i].size(); ++k) {
      if (k <= l)
        c[k] = mul(mul(c[k - 1], l - k + 1), power(k, M - 2));

      for (int x = k; x > 0; --x)
        if (x <= l)
          val[k] = norm(val[k] + mul(c[x], C(k - 1, x - 1)));
    }

    int index = 0;

    for (int k = 0; k <= n; ++k) {
      ll res = (k == 0 ? 1 : 0);

      for (int j = 0; j < i; ++j)
        res = norm(res + dp[j][k]);

      int cnt = 0;
      for (auto j : a[i])
        if (j > k) {
          cnt++;

          dp[i][j] = norm(dp[i][j] + mul(res, val[cnt]));
        }

      ans = norm(ans + dp[i][k]);
    }
  }

  cout << ans;

  return 0;
}

Compilation message

boat.cpp: In function 'int main()':
boat.cpp:75:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 1; i < ret.size(); ++i)
                   ~~^~~~~~~~~~~~
boat.cpp:77:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       if (i == ret.size() || ret[i] != ret[i + 1]) {
           ~~^~~~~~~~~~~~~
boat.cpp:90:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < seg.size(); ++i) {
                   ~~^~~~~~~~~~~~
boat.cpp:99:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int i = 0; i < seg.size(); ++i) {
                   ~~^~~~~~~~~~~~
boat.cpp:106:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int k = 1; k <= a[i].size(); ++k) {
                     ~~^~~~~~~~~~~~~~
boat.cpp:115:9: warning: unused variable 'index' [-Wunused-variable]
     int index = 0;
         ^~~~~

Subtask #1
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 430 ms 2424 KB Output is correct
2 Correct 436 ms 2552 KB Output is correct
3 Correct 429 ms 2552 KB Output is correct
4 Correct 434 ms 2388 KB Output is correct
5 Correct 431 ms 2552 KB Output is correct
6 Correct 434 ms 2376 KB Output is correct
7 Correct 429 ms 2448 KB Output is correct
8 Correct 436 ms 2424 KB Output is correct
9 Correct 447 ms 2424 KB Output is correct
10 Correct 429 ms 2560 KB Output is correct
11 Correct 435 ms 2552 KB Output is correct
12 Correct 431 ms 2552 KB Output is correct
13 Correct 431 ms 2424 KB Output is correct
14 Correct 435 ms 2552 KB Output is correct
15 Correct 430 ms 2552 KB Output is correct
16 Correct 20 ms 896 KB Output is correct
17 Correct 21 ms 896 KB Output is correct
18 Correct 20 ms 896 KB Output is correct
19 Correct 21 ms 1024 KB Output is correct
20 Correct 20 ms 896 KB Output is correct

Subtask #2
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 430 ms 2424 KB Output is correct
2 Correct 436 ms 2552 KB Output is correct
3 Correct 429 ms 2552 KB Output is correct
4 Correct 434 ms 2388 KB Output is correct
5 Correct 431 ms 2552 KB Output is correct
6 Correct 434 ms 2376 KB Output is correct
7 Correct 429 ms 2448 KB Output is correct
8 Correct 436 ms 2424 KB Output is correct
9 Correct 447 ms 2424 KB Output is correct
10 Correct 429 ms 2560 KB Output is correct
11 Correct 435 ms 2552 KB Output is correct
12 Correct 431 ms 2552 KB Output is correct
13 Correct 431 ms 2424 KB Output is correct
14 Correct 435 ms 2552 KB Output is correct
15 Correct 430 ms 2552 KB Output is correct
16 Correct 20 ms 896 KB Output is correct
17 Correct 21 ms 896 KB Output is correct
18 Correct 20 ms 896 KB Output is correct
19 Correct 21 ms 1024 KB Output is correct
20 Correct 20 ms 896 KB Output is correct
21 Incorrect 656 ms 5240 KB Output isn't correct
22 Halted 0 ms 0 KB -

Subtask #3
0 / 27.0

# Verdict Execution time Memory Grader output
1 Incorrect 14 ms 1280 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 42.0

# Verdict Execution time Memory Grader output
1 Correct 430 ms 2424 KB Output is correct
2 Correct 436 ms 2552 KB Output is correct
3 Correct 429 ms 2552 KB Output is correct
4 Correct 434 ms 2388 KB Output is correct
5 Correct 431 ms 2552 KB Output is correct
6 Correct 434 ms 2376 KB Output is correct
7 Correct 429 ms 2448 KB Output is correct
8 Correct 436 ms 2424 KB Output is correct
9 Correct 447 ms 2424 KB Output is correct
10 Correct 429 ms 2560 KB Output is correct
11 Correct 435 ms 2552 KB Output is correct
12 Correct 431 ms 2552 KB Output is correct
13 Correct 431 ms 2424 KB Output is correct
14 Correct 435 ms 2552 KB Output is correct
15 Correct 430 ms 2552 KB Output is correct
16 Correct 20 ms 896 KB Output is correct
17 Correct 21 ms 896 KB Output is correct
18 Correct 20 ms 896 KB Output is correct
19 Correct 21 ms 1024 KB Output is correct
20 Correct 20 ms 896 KB Output is correct
21 Incorrect 656 ms 5240 KB Output isn't correct
22 Halted 0 ms 0 KB -