Submission #1233613

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233613		Ariadna	Trains (BOI24_trains)	C++20	0 / 100	17 ms	2120 KiB

Main

#include <bits/stdc++.h>
#define ll long long
using namespace std;

const int mod = 1e9+7, N = 1e5;
ll dp[N];

int main() {
    int n;
    cin >> n;
    vector<int> d(n), x(n);
    for (int i = 0; i < n; ++i) cin >> d[i] >> x[i];
    vector<int> final(n);
    vector<vector<int>> ends(n);
    for (int i = 0; i < n; ++i) {
        final[i] = min(n-1, i+d[i]*x[i]);
        ends[final[i]].push_back(i);
    }

    ll sum = dp[0] = 1;
    for (int i = 1; i < n; ++i) {
        dp[i] = sum;
        sum += dp[i];
        for (int a: ends[i]) sum -= dp[a];
        sum %= mod;
    }
    
    ll tot = 0;
    for (int i = 0; i < n; ++i) {
        tot += dp[i];
        tot%=mod;
    }
    cout << tot << endl;

    return 0;
}

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