Submission #1111602

#	Time	Username	Problem	Language	Result	Execution time	Memory
1111602		justin271828	Trains (BOI24_trains)	C++14	16 / 100	42 ms	3524 KiB

Main

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

int main() {
    long long N;
    cin >> N;
    if (N == 1) {
        cout << 1;
        return 0;
    }
    long long d[N];
    long long x[N];
    for (long long i = 0; i < N; i++) {
        cin >> d[i] >> x[i];
    }
    long long diff[N];
    memset(diff, 0, sizeof(diff));
    diff[0] = 1;
    diff[1] = -1;
    long long dsum = 0;
    for (int i = 0; i < N-1; i++) {
        dsum += diff[i];
        if (dsum < 0) dsum += 1000000007;
        dsum %= 1000000007;
        diff[i+1] += dsum;
        if (diff[i+1] < 0) dsum += 1000000007;
        diff[i+1] %= 1000000007;
        if (i+1+x[i] < N) {
            diff[i+1+x[i]] -= dsum;
            if (diff[i+1+x[i]] < 0) dsum += 1000000007;
            diff[i+1+x[i]]%=1000000007;
        }
    }
    long long sum[N];
    sum[0] = 1;
    for (int i = 1; i < N; i++) {
        sum[i] = sum[i-1]+diff[i];
        if (sum[i] < 0) sum[i] += 1000000007;
        sum[i]%=1000000007;
    }
    long long ans = 0;
    for (long long i: sum) {
        ans += i;
        ans %= 1000000007;
    }
    cout << ans;
    return 0;
}

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