Ярику прикол

//
//  main.cpp
//  zadacha
//
//  Created by Yaroslav Monastyrev on 24.10.2021.
//

#include <iostream>
#include <stack>
#include <list>
#include <vector>

using namespace std;

class Graph {
    int V;
    vector<int> order;
    vector<vector<int>> adj;

    void DFS_1(int v, vector<bool> &used, stack<int> &Stack);
    void DFS_2(int v, vector<bool> &used);

public:

    Graph(int V);
    Graph reverse();
    void addEdge(int v, int w);
    void mainSolve();

};

Graph :: Graph(int V) {
    this -> V = V;
    adj = vector<vector<int>> (V);
}

void Graph::addEdge(int v, int w) {
    adj[v].push_back(w);
}

void Graph :: DFS_1(int v, vector<bool> &used, stack<int> &Stack){
    used[v] = true;
    for (auto i: adj[v]){
        if (!used[i]){
            DFS_1(i, used, Stack);
        }
    }
    Stack.push(v);
}

void Graph :: DFS_2(int v, vector<bool> &used){
    used[v] = true;
    order.push_back(v);
    for (auto i: adj[v]){
        if (!used[i]){
            DFS_2(i, used);
        }
    }
}
Graph Graph :: reverse(){
    Graph Gr(V);
    for(int i = 0; i < V; i++){
        for(auto j: adj[i]){
            Gr.adj[j].push_back(i);
        }

    }
    return Gr;
}

void Graph :: mainSolve() {
    vector<bool> used(V);
    stack <int> Stack;
    for(int i = 0; i < V;i++) {
        if (!used[i]){
            DFS_1(i, used, Stack);
        }
    }
    Graph Gr1 = reverse();
    for(int i = 0; i < V;i++) {
        used[i] = false;
    }
    vector<int> answer(V);
    int count = 0;
    while (!Stack.empty()) {
        int a = Stack.top();
        Stack.pop();
        if(!used[a]){
            Gr1.DFS_2(a, used);
            for (int i = 0; i < Gr1.order.size(); ++i) {
                answer[Gr1.order[i]] = count + 1;
            }
            count++;
            Gr1.order.clear();
        }
    }
    cout << count << endl;
    for (int i = 0; i < answer.size(); ++i) {
        cout << answer[i] << " ";
    }
}

int main(){
    int n, m;
    cin >> n >> m;
    Graph graph(n);

    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        graph.addEdge(a - 1, b - 1);
    }
    graph.mainSolve();
}