Submission #967952

#	Time	Username	Problem	Language	Result	Execution time	Memory
967952		duckindog	Boat (APIO16_boat)	C++17	31 / 100	1525 ms	524288 KiB

boat

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
 
using namespace std;
 
const int N = 500 + 10,
          M = 1'000'000'007;
int n;
int a[N], b[N];

int f[2][1'000'010];
 
int32_t main() { 
  cin.tie(0)->sync_with_stdio(0);
 
  cin >> n;
  for (int i = 1; i <= n; ++i) cin >> a[i] >> b[i];
 
  vector<int> rrh;
  for (int i = 1; i <= n; ++i) { 
    for (int j = a[i]; j <= b[i]; ++j) rrh.push_back(j);
  }
  sort(rrh.begin(), rrh.end());
  rrh.resize(unique(rrh.begin(), rrh.end()) - rrh.begin());

  f[0][0] = 1;
  for (int j = 1; j <= rrh.size(); ++j) f[0][j] = 1;
 
  for (int i = 1; i <= n; ++i) { 
    bool id = i & 1, p = id ^ 1;
    
    int it = lower_bound(rrh.begin(), rrh.end(), a[i]) - rrh.begin() + 1;

    auto add = [&](auto& value, const auto& delta) {
      value += delta;
      if (value >= M) value -= M;
    };
    
    f[id][0] = f[p][0];
    for (int j = 1; j <= rrh.size(); ++j) {
      f[id][j] = f[id][j - 1];
      if (j < it || j > b[i] - a[i] + it) {
        add(f[id][j], f[p][j]);
        add(f[id][j], M - f[p][j - 1]);
      } else {
        add(f[id][j], f[p][j]);
      }
    }
  }
  
  cout << f[n & 1][rrh.size()] - 1 << "\n";
  cerr << 1.0 * clock() / CLOCKS_PER_SEC << "\n";
}

Compilation message (stderr)

boat.cpp: In function 'int32_t main()':
boat.cpp:28:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |   for (int j = 1; j <= rrh.size(); ++j) f[0][j] = 1;
      |                   ~~^~~~~~~~~~~~~
boat.cpp:41:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     for (int j = 1; j <= rrh.size(); ++j) {
      |                     ~~^~~~~~~~~~~~~

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