제출 #202589

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
202589		pr3pony	Boat (APIO16_boat)	C++14	100 / 100	438 ms	4472 KiB

boat

#include<bits/stdc++.h>
using namespace std;
const int N = 505, MOD = 1e9 + 7;
typedef long long ll;
vector<int> val;
typedef array<int, 2> ar;
ar p[N];
ll dp[2 * N][N], inv[N];
int main()
{
    int n;
    cin >> n;
    val = {-1};
    for (int i = 1; i <= n; ++i) {
        cin >> p[i][0] >> p[i][1];
        ++p[i][1];
        val.push_back(p[i][0]);
        val.push_back(p[i][1]);
    }
    sort(val.begin(), val.end());
    val.resize(unique(val.begin(), val.end()) - val.begin());
    int w = val.size();

    inv[1] = 1;
    for (int i = 2; i <= n; ++i)
        inv[i] = (MOD - MOD / i) * inv[MOD % i] % MOD;

    for (int i = 0; i < w; ++i)
        dp[i][0] = 1;
    for (int b = 1; b <= n; ++b) {
        for (int i = w - 1; i > 0; --i) 
            if (p[b][0] <= val[i - 1] && val[i] <= p[b][1]) {
                int cn = val[i] - val[i - 1];
                for (int j = min(cn, b); j >= 1; --j)
                    (dp[i][j] += dp[i][j - 1] * (cn - j + 1) % MOD * inv[j]) %= MOD;
            }
        for (int i = 1; i <= w; ++i)
            dp[i][0] = accumulate(dp[i - 1], dp[i - 1] + n + 1, 0ll) % MOD;
    }
    cout << (dp[w][0] + MOD - 1) % MOD << endl;
}

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