제출 #1095467

#제출 시각아이디문제언어결과실행 시간메모리
1095467LaMatematica14Trains (BOI24_trains)C++17
0 / 100
188 ms122452 KiB
#include <bits/stdc++.h>
using namespace std;
const long long rad = 316;
const long long mod = 1e9+7;

int main() {
    long long N; cin >> N;
    vector<long long> d(N), x(N);
    for (int i = 0; i < N; i++) cin >> x[i] >> d[i];
    for (int i = 0; i < N; i++) {
        if (x[i] == 0) d[i] = 0;
        else d[i] = min(d[i], (N-i-1)/x[i]);
    }
    vector<vector<long long>> pr(rad, vector<long long> (N+1, 0));
    vector<long long> dp(N, 1);
    for (int i = N-1; i >= 0; i--) {
        if (x[i] >= rad) {
            for (int k = i+x[i]; k < min(N, i+d[i]*x[i]+1); k+= x[i]) {
                dp[i] += dp[k];
                dp[i] %= mod;
            }
        }
        else {
            if (d[i] > 0) {
                dp[i] +=  pr[x[i]][i+x[i]]-pr[x[i]][i+d[i]*x[i]+1];
                dp[i] %= mod;
            }
        }
        for (int j = 1; j <= min(rad-1, N-i); j++) {
            pr[j][i] = dp[i]+pr[j][i+j];
            pr[j][i] %= mod;
        }
    }
    cout << dp[0];
}
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