Submission #1133910

#	Time	Username	Problem	Language	Result	Execution time	Memory
1133910		huoi	Trains (BOI24_trains)	C++17	8 / 100	850 ms	1114112 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define int long long
#define INF 9e18
#define M 1000000007

void solve() {
    int n;
    cin >> n;

    vector<int> d(n + 1), x(n + 1);
    bool sub3 = true;
    for (int i = 1; i <= n; i++) {
        cin >> d[i] >> x[i];
        if (d[i] != 1) sub3 = false;
    }

    if (sub3) {
        vector<int> dp(n + 1, 1);
        vector<int> dpp(n + 2);
        dpp[n] = 1;
        for (int i = n - 1; i >= 1; i--) {
            dp[i] = (dp[i] + dpp[i + 1] - dpp[min(i + x[i] + 1, n + 1)]) % M;
            dpp[i] = (dpp[i + 1] + dp[i]) % M;
        }

        cout << dp[1];
        return;
    }

    vector<vector<int>> routes(n + 1);
    for (int i = 1; i <= n; i++) {
        for (int j = i + d[i]; j <= n; j += d[i]) {
            if (routes[i].size() == x[i] || d[i] == 0) break;
            routes[i].push_back(j);
        }
    }

    vector<int> dp(n + 1, 1);

    for (int i = n; i >= 1; i--) {
        for (int j : routes[i]) {
            dp[i] = (dp[i] + dp[j]) % M;
        }
    }

    cout << dp[1];
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    solve();
    return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 0 / 13
• Subtask 3: 0 / 16
• Subtask 4: 0 / 34
• Subtask 5: 0 / 29