Cod sursa(job #3252273)

Utilizator benjamin2205Zeic Beniamin benjamin2205 Data 28 octombrie 2024 23:12:38
Problema Sortare topologica Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.74 kb
#include <iostream>
#include <fstream>
#include <bits/stdc++.h>

using namespace std;

ifstream fin("sortaret.in");
ofstream gout("sortaret.out");

int N_VERTEX;
int M_EDGES;

int in_degree[50000] = {0};
int position_counter[50001] = {0};

vector<int> edges[50001];
vector<int> sorted;

void read() {
    int x;
    int y;
    
    fin >> N_VERTEX;
    fin >> M_EDGES;
    
    // Read all edges in adjacency list
    for (int i = 0; i < M_EDGES; ++i) {
        fin >> x >> y;
        edges[x].push_back(y);
        ++in_degree[y];
    }
}

int find_root() {
    for (int i = 1; i < N_VERTEX; ++i) {
        if (in_degree[i] == 0) {
            // mark it as visited
            return i;
        }
    }
}

int remove_vertex(int vertex) {
    // Decrease incoming score of connected nodes
    for (int outgoing = 0; outgoing < edges[vertex].size(); ++outgoing) {
        --in_degree[edges[vertex][outgoing]];
    }
    // Empty vector of edges outgoing from vertex - not mandatory
    edges[vertex].clear();
    // Mark as visited
    in_degree[vertex] = -1;
}

void topological_sort(int root) {
    int count_removed = 0;

    sorted.push_back(root);
    remove_vertex(root);
    count_removed = 1;
    
    while (count_removed < N_VERTEX) {
        for (int i = 1; i <= N_VERTEX; ++i) {
            if (in_degree[i] == 0) {
                sorted.push_back(i);
                remove_vertex(i);
                ++count_removed;
                // bad implementation
            }
        }
    }
}

void write() {
    for (int i = 0; i < sorted.size(); ++i) {
        gout << sorted[i] << " ";
    }
    gout << "\n";
}


int main() {
    read();
    
    int root = find_root();
    topological_sort(root);

    write();

    fin.close();
    gout.close();

    return 0;
}