Submission #946741

#	Time	Username	Problem	Language	Result	Execution time	Memory
946741		Ice_man	Boat (APIO16_boat)	C++14	100 / 100	472 ms	8616 KiB

boat

#include <iostream>
#include <chrono>
#include <set>
#include <vector>
#include <map>
#include <cstring>
#include <algorithm>

#define maxn 1005
#define maxlog 20
#define mod 1000000007
#define INF 1000000010
#define LINF 1000000000000000005
#define endl '\n'
#define pb(x) push_back(x)
#define X first
#define Y second
#define control cout<<"passed"<<endl;

#pragma GCC optimize("O3" , "Ofast" , "unroll-loops" , "fast-math")
#pragma GCC target("avx2")

using namespace std;

std::chrono::high_resolution_clock::time_point startT, currT;
constexpr double TIME_MULT = 1;

double timePassed()
{
    using namespace std::chrono;
    currT = high_resolution_clock::now();
    double time = duration_cast<duration<double>>(currT - startT).count();
    return time * TIME_MULT;
}

long long m[maxn * 2];

void inv_mod()
{
    m[1] = 1;
    for(long long i = 2; i < maxn * 2; i++)
        m[i] = (mod / i) * (mod - m[mod % i]) % mod;
}


long long l[maxn], r[maxn];
long long n;
long long dp[maxn][maxn];

void read()
{
    cin >> n;

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

long long ans = 0;
vector <long long> v;

void pre()
{
    for(long long i = 1; i <= n; i++)
    {
        v.pb(l[i]);
        v.pb(r[i] + 1);
    }

    sort(v.begin(), v.end());
    v.resize(unique(v.begin(), v.end()) - v.begin());

    for(long long i = 1; i <= n; i++)
    {
        l[i] = lower_bound(v.begin(), v.end(), l[i]) - v.begin() + 1;
        r[i] = lower_bound(v.begin(), v.end(), r[i] + 1) - v.begin() + 1;
    }

}






void calc_dp()
{
    dp[0][0] = 1;

    long long a , br , c;

    for(long long i = 1; i < v.size(); i++)
    {
        dp[i][0] = 1;

        for(long long j = 1; j <= n; j++)
        {
            dp[i][j] = dp[i - 1][j];

            if(l[j] > i)
                continue;

            if(i >= r[j])
                continue;

            a = v[i] - v[i - 1];
            br = 1;
            c = v[i] - v[i - 1];

            for(long long k = j - 1; k > -1; k--)
            {
                dp[i][j] += dp[i - 1][k] * c;
                dp[i][j] %= mod;

                if(i >= l[k] && i < r[k])
                {
                    c *= (a + br);
                    c %= mod;

                    c *= m[br + 1];
                    c %= mod;
                    br++;
                }

            }


        }

    }

    long long ans = 0;

    for(long long i = 1; i <= n; i++)
    {
        ans += dp[v.size() - 1][i];
        ans %= mod;
    }

    cout << ans << endl;
}





int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    //startT = std::chrono::high_resolution_clock::now();

    inv_mod();

    /**for(long long i = 1; i <= 10; i++)
        cout << m[i] << " ";
    cout << endl;*/

    read();
    pre();
    calc_dp();


    return 0;
}

Compilation message (stderr)

boat.cpp: In function 'void calc_dp()':
boat.cpp:91:28: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |     for(long long i = 1; i < v.size(); i++)
      |                          ~~^~~~~~~~~~

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