제출 #558513

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
558513		hoanghq2004	Boat (APIO16_boat)	C++14	0 / 100	650 ms	4316 KiB

boat

#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;

const int N = 510;
const int mod = 1e9 + 7;

int n, f[N * 2][N], g[N * 2][N], C[N][N];
int L[N], R[N], cur[N], inv[N];

void add(int& a, int b) {
    a += b;
    if (a >= mod) a -= mod;
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n;
    vector <int> dta = {0};
    for (int i = 1; i <= n; ++i) {
        cin >> L[i] >> R[i];
        --L[i];
        dta.push_back(L[i]), dta.push_back(R[i]);
    }
    sort(dta.begin(), dta.end());
    dta.erase(unique(dta.begin(), dta.end()), dta.end());
    int m = dta.size();
    C[0][0] = 1;
    for (int i = 1; i < N; ++i) {
        C[i][0] = 1;
        for (int j = 1; j <= i; ++j)
            C[i][j] = (C[i - 1][j] + C[i - 1][j - 1]) % mod;
    }
    auto power = [&](int a, int n) {
        int ans = 1;
        for (; n; n >>= 1, a = 1LL * a * a % mod)
            if (n & 1) ans = 1LL * ans * a % mod;
        return ans;
    };
    inv[0] = 1;
    for (int i = 1, fact = 1; i <= n; ++i, fact = 1LL * fact * i % mod) {
        inv[i] = power(fact, mod - 2);
    }
    auto coef = [&](int n, int k) {
        if (k > n - k) k = n - k;
        int ans = inv[k];
        for (int i = n - k + 1; i <= n; ++i) ans = 1LL * ans * i % mod;
        return ans;
    };
    for (int i = 0; i < m; ++i) f[0][i] = 1;
    for (int s = 1; s < m; ++s) {
        int d = dta[s] - dta[s - 1];
        for (int i = 0; i <= n; ++i) cur[i] = coef(d, i);
        for (int i = 0; i <= n; ++i) {
            for (int j = 0; j < i; ++j) {
                add(g[s][i], 1LL * C[i - 1][j] * cur[j + 1] % mod);
            }
        }
    }
//    cout << g[1][2] << "\n";
    int ans = 0;
    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j < m; ++j) {
            f[i][j] = f[i][j - 1];
            if (L[i] >= dta[j] || dta[j] > R[i]) continue;
//            if (i == 2) cout << j << '\n';
            int cnt = 0;
            for (int k = i; k > 0; --k) {
                cnt += (L[k] < dta[j] && dta[j] <= R[k]);
//                if (i == 2) cout << k - 1 << ' ' << j - 1 << " " << cnt << " " << g[j][cnt] << "aaa\n";
                add(f[i][j], 1LL * f[k - 1][j - 1] * g[j][cnt] % mod);
            }
        }
        add(ans, f[i][m - 1]);
//        cout << f[i][m - 1] << '\n';
    }
    cout << ans;
//    f[n][m - 1] - 1;
}

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