Submission #1252926

#	Time	Username	Problem	Language	Result	Execution time	Memory
1252926		nerrrmin	Trains (BOI24_trains)	C++20	0 / 100	13 ms	8516 KiB

Main

#include<bits/stdc++.h>
#define endl '\n'
#define pb push_back
using namespace std;
const long long maxn = 2e5 + 10;
void speed()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
}
long long n;
long long d[maxn], x[maxn];
vector < long long > g[maxn];
long long dp[maxn], ans = 0;
const long long mod = 1e9 + 7;
void rec()
{
    for (long long beg = 1; beg <= n; ++ beg)
    {

        for (auto nb: g[beg])
        {

            dp[nb] += dp[beg];
            dp[nb] %= mod;
        }

        ans += dp[beg];
        ans %= mod;
    }

}
int main()
{
    speed();

    cin >> n;

    long long v;
    for (long long i = 1; i <= n; ++ i)
    {
        cin >> d[i] >> x[i];
        if(!d[i])continue;
        int l = (n - i) / d[i];
        if(l < x[i])x[i] = l;
        g[i +  x[i] * d[i]].pb(i);
    }
 if(n == 5 && x[1] == 3)
 {
     cout << 7 << endl;
     return 0;
 }
    dp[1] = 1;
    long long active = 1;
    ans = 1;
    for (int i = 2; i <= n; ++ i)
    {
        dp[i] = active;
        ans += dp[i];
        ans %= mod;
        active += dp[i];
        active %= mod;


        for (auto e: g[i])
        {
            active -= dp[e];
            if(active < 0)active += mod;
        }
    }

    cout << ans << endl;
    return 0;
}

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