Submission #1233660

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233660		Ariadna	Trains (BOI24_trains)	C++20	100 / 100	363 ms	252584 KiB

Main

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

const int mod = 1e9+7, N = 1e5, S = 317;
int dp[N];

signed 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);
    for (int i = 0; i < n; ++i) final[i] = i+d[i]*(x[i]+1);
    dp[n-1] = 1;
    
    vector<vector<int>> suff(S, vector<int>(n+S, 0));
    for (int i = n-1; i >= 0; --i) {
        dp[i] = 1;
        if (d[i] >= S) {
            for (int j = i+d[i]; j <= min(n, i+d[i]*x[i]); j+=d[i]) {
                dp[i] += dp[j];
                dp[i] %= mod;
            }
        } else if (d[i] > 0) {
            dp[i] += suff[d[i]][i+d[i]];
            if (final[i] < n) dp[i] = (dp[i]-suff[d[i]][final[i]])%mod;
            dp[i] = (dp[i]+mod)%mod;
        }
        for (int j = 1; j < S; ++j) suff[j][i] = (suff[j][i+j]+dp[i])%mod; 
    }
    
    cout << dp[0] << endl;

    return 0;
}

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