Submission #1276709

#	Time	Username	Problem	Language	Result	Execution time	Memory
1276709		HiepVu217	Trains (BOI24_trains)	C++20	100 / 100	253 ms	125708 KiB

Main

#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 17, B = 317, M = 1e9 + 7;
int n, d[N], x[N], f[N], s[N][B];
void add (int &a, long long b)
{
    a += b;
    if (a >= M)
    {
        a -= M;
    }
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    for (int i = 1; i <= n; ++i)
    {
        cin >> d[i] >> x[i];
    }
    for (int i = n; i; --i)
    {
        int c = d[i];
        f[i] = 1;
        if (c)
        {
            int k = min (x[i], (n - i) / d[i]);
            if (k <= B)
            {
                for (int j = i + c; j <= i + k * c; j += c)
                {
                    add (f[i], f[j]);
                }
            }
            else
            {
                add (f[i], s[i + c][c] - s[i + (k + 1) * c][c] + M);
            }
        }
        for (int j = 1; j < B; ++j)
        {
            s[i][j] = (s[i + j][j] + f[i]) % M;
        }
    }
    cout << f[1];
}

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