Submission #96025

#	Time	Username	Problem	Language	Result	Execution time	Memory
96025		alextodoran	Shell (info1cup18_shell)	C++14	100 / 100	741 ms	172996 KiB

shell

#include <bits/stdc++.h>

#define NM 3000002
#define ll long long

using namespace std;

const ll MOD = 1e9+7;

vector <int> ine[NM], oute[NM];

int n, m, p;

int v[NM];
bool spv[NM];

int g[NM];

queue <int> q;

int ord[NM];

int vo[NM];

bool fs (int a, int b)
{
    return ord[a] < ord[b];
}

ll dp[NM];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> m >> p;
    for(int i = 1; i <= p; i++)
    {
        cin >> v[i];
        spv[v[i]] = 1;
    }
    for(int i = 1; i <= m; i++)
    {
        int u, v;
        cin >> u >> v;
        ine[v].push_back(u);
        oute[u].push_back(v);
        g[v]++;
    }
    for(int i = 1; i <= n; i++)
        if(g[i] == 0)
        {
            ord[i] = 1;
            q.push(i);
        }
    while(!q.empty())
    {
        auto f = q.front();
        q.pop();
        for(auto e : oute[f])
        {
            g[e]--;
            if(g[e] == 0)
            {
                ord[e] = ord[f] + 1;
                q.push(e);
            }
        }
    }
    for(int i = 2; i <= p; i++)
        if(ord[v[i]] <= ord[v[i - 1]])
        {
            cout << "0\n";
            return 0;
        }
    for(int i = 1; i <= n; i++)
        vo[i] = i;
    sort(vo + 1, vo + n + 1, fs);
    int last = 0;
    for(int i = 1; i <= n; i++)
        if(vo[i] != 1)
        {
            if(last != 0)
                for(auto e : ine[vo[i]])
                    if(ord[e] > ord[last] || e == last)
                    {
                        dp[vo[i]] += dp[e];
                        if(dp[vo[i]] >= MOD)
                            dp[vo[i]] -= MOD;
                    }
            if(spv[vo[i]])
                last = vo[i];
        }
        else
        {
            if(last == 0)
                dp[1] = 1;
            last = 1;
        }
    cout << dp[n] << "\n";
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 45 / 45
• Subtask 3: 20 / 20
• Subtask 4: 25 / 25