Submission #1237307

#TimeUsernameProblemLanguageResultExecution timeMemory
1237307zadniprovskaTrains (BOI24_trains)C++20
0 / 100
2094 ms1096 KiB
#include <bits/stdc++.h>

using namespace std;


#define ll long long

const ll DIM = 1e5 + 7;
const ll mod = 1e9 + 7;

ll dp[DIM];

int main(){
    ios::sync_with_stdio(false);cin.tie(nullptr); cout.tie(nullptr);
    

    ll n;
    cin >> n;

    dp[1] = 1;
    for (int i=1; i<=n; i++) {
        ll d, x;
        cin >> d >> x;

        if (d == 0) continue;

        for (int j=i+d; j<=min(n, i + x*d); j++) {
            dp[j] += dp[i];
            dp[j] %= mod;
        }
    }

    ll answer = 0;
    for (int i=1; i<=n; i++) {
        answer += dp[i];
        answer %= mod;
    }
    cout << answer << endl;

}
;
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