Submission #1095547

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095547		LaMatematica14	Trains (BOI24_trains)	C++17	42 / 100	414 ms	252284 KiB

Main

#include <bits/stdc++.h>
using namespace std;
const long long rad = 316;
const long long mod = 1e9+7;

long long solve(long long N, vector<long long> &d, vector<long long> &x) {
    vector<vector<long long>> pr(rad, vector<long long> (N+rad, 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]+1)*x[i]];
                dp[i] %= mod;
            }
        }
        for (int j = 1; j < rad; j++) {
            if (i+j < N) {
                pr[j][i] = dp[i]+pr[j][i+j];
                pr[j][i] %= mod;
            } else pr[j][i] = dp[i];
        }
    }
    return dp[0];
}

long long solve2(int N, vector<long long> &d, vector<long long> &x) {
    vector<long long> dp(N, 1);
    for (int i = N-1; i >= 0; i--) {
        if (x[i] == 0) continue;
        int k = 1;
        for (int j = i+x[i]; j < N; j+=x[i]) {
            if (k > d[i]) break;
            dp[i] += dp[j]; dp[i] %= mod;
            k++;
        }
    }
    return dp[0];
}

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]);
    }
    
    cout << solve(N, d, x);
}

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