Przejdź do treści

Sortowanie topologiczne

Opis problemu

Implementacja

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
#include <iostream>
#include <vector>

using namespace std;

vector<int> topologicalSort(vector<vector<int> > &graph) {
    vector<int> inRanks = vector<int>(graph.size());
    vector<bool> removed = vector<bool>(graph.size());
    vector<int> result;
    bool change;

    for (int i = 0; i < graph.size(); i++) {
        for (int j = 0; j < graph[i].size(); j++) {
            inRanks[graph[i][j]]++;
        }
    }

    change = true;

    while (change && result.size() < graph.size()) {
        change = false;

        for (int i = 0; i < graph.size(); i++) {
            if (removed[i] || inRanks[i] > 0) {
                continue;
            }

            change = true;
            result.push_back(i);
            removed[i] = true;

            for (int j = 0; j < graph[i].size(); j++) {
                inRanks[graph[i][j]]--;
            }
        }
    }

    return result;
}

int main() {
    vector<vector<int> > graph = {
        {2},
        {0, 2},
        {},
        {1, 0, 4},
        {2, 1},
        {0, 4},
    };

    vector<int> result = topologicalSort(graph);

    if (result.size() < graph.size()) {
        cout << "Graph has a cycle" << endl;
    } else {
        for (int el : result) {
            cout << el << " ";
        }

        cout << endl;
    }

    return 0;
}

Opis implementacji

Przykładowy graf wykorzystany w implementacji

http://graphonline.ru/en/?graph=VzWmgsofErPDNlfp