7 контест 1, 2 задача Даша

#include <iostream>
#include <vector>

using namespace std;

vector<vector<int>> g(20000);
vector<vector<int>> g_reversed(20000);
vector<int> used(20000);
vector<int> order;
vector<int> componenta;

void dfs(int v){
    used[v] = 1;
    for (int i = 0; i < g[v].size(); i++){
        int curr_v = g[v][i];
        if (used[curr_v] == 0)
            dfs(curr_v);
    }
    order.push_back(v);
}

void dfs_reversed(int v){
    used[v] = 1;
    componenta.push_back(v);
    for (int i = 0; i < g_reversed[v].size(); i++){
        int curr_v = g_reversed[v][i];
        if (used[curr_v] == 0)
            dfs_reversed(curr_v);
    }
}

int main() {
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; i++){
        int a, b;
        cin >> a >> b;
        g[a - 1].push_back(b - 1);
        g_reversed[b - 1].push_back(a - 1);
    }

    for (int i = 0; i < n; i++){
        if (used[i] == 0)
            dfs(i);
    }

    for (int i = 0; i < n; i++)
        used[i] = 0;

    int k = 1;
    vector<int> res(n);
    for (int i = 0; i < n; i++){
        int curr_v = order[n - i - 1];
        if (used[curr_v] == 0){
            dfs_reversed(curr_v);
            for (int j = 0; j < componenta.size(); j++){
                res[componenta[j]] = k;
            }
            k++;
            componenta.clear();
        }
    }
    cout << k - 1 << endl;
    for (int i = 0; i < n; i++){
        cout << res[i] << ' ';
    }
}

// 2 задача

#include <iostream>
#include <vector>

using namespace std;

vector<vector<int>> g(20000);
vector<vector<int>> g_reversed(20000);
vector<int> used(20000);
vector<int> order;
vector<int> componenta;

void dfs(int v){
    used[v] = 1;
    for (int i = 0; i < g[v].size(); i++){
        int curr_v = g[v][i];
        if (used[curr_v] == 0)
            dfs(curr_v);
    }
    order.push_back(v);
}

void dfs_reversed(int v){
    used[v] = 1;
    componenta.push_back(v);
    for (int i = 0; i < g_reversed[v].size(); i++){
        int curr_v = g_reversed[v][i];
        if (used[curr_v] == 0)
            dfs_reversed(curr_v);
    }
}

int main() {
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; i++){
        int a, b;
        cin >> a >> b;
        g[a - 1].push_back(b - 1);
        g_reversed[b - 1].push_back(a - 1);
    }

    for (int i = 0; i < n; i++){
        if (used[i] == 0)
            dfs(i);
    }

    for (int i = 0; i < n; i++)
        used[i] = 0;

    int k = 1;
    vector<int> componenta_number(n);
    vector<int> componenta_v;
    for (int i = 0; i < n; i++){
        int curr_v = order[n - i - 1];
        if (used[curr_v] == 0){
            dfs_reversed(curr_v);
            for (int j = 0; j < componenta.size(); j++){
                componenta_number[componenta[j]] = k;
            }
            componenta_v.push_back(componenta[0]);
            k++;
            componenta.clear();
        }
    }
    vector<int> f_is(k - 1); // 1 - пожарную станцию размещать не надо

    int cnt = k;
    for (int i = 0; i < n; i++){
        for (int j = 0; j < g[i].size(); j++){
            int a = i;
            int b = g[i][j];
            if (componenta_number[a] != componenta_number[b]){
                f_is[componenta_number[a] - 1] = 1;
                cnt--;
            }
        }
    }
    cout << cnt << endl;
    for (int i = 0; i < k - 1; i++){
        if (f_is[i] == 0)
            cout << componenta_v[i] + 1 << endl;
    }
}