拓扑排序

原理及其Java实现
c++版本
c++版本的dfs

// A C++ program to print topological sorting of a DAG#include<iostream>#include <list>#include <stack>using namespace std;// Class to represent a graphclass Graph{    int V;    // No. of vertices'    // Pointer to an array containing adjacency listsList    list<int> *adj;    // A function used by topologicalSort    void topologicalSortUtil(int v, bool visited[], stack<int> &Stack);public:    Graph(int V);   // Constructor     // function to add an edge to graph    void addEdge(int v, int w);    // prints a Topological Sort of the complete graph    void topologicalSort();};Graph::Graph(int V){    this->V = V;    adj = new list<int>[V];}void Graph::addEdge(int v, int w){    adj[v].push_back(w); // Add w to v’s list.}// A recursive function used by topologicalSortvoid Graph::topologicalSortUtil(int v, bool visited[],                                 stack<int> &Stack){    // Mark the current node as visited.    visited[v] = true;    // Recur for all the vertices adjacent to this vertex    list<int>::iterator i;    for (i = adj[v].begin(); i != adj[v].end(); ++i)        if (!visited[*i])            topologicalSortUtil(*i, visited, Stack);    // Push current vertex to stack which stores result    Stack.push(v);}// The function to do Topological Sort. It uses recursive // topologicalSortUtil()void Graph::topologicalSort(){    stack<int> Stack;    // Mark all the vertices as not visited    bool *visited = new bool[V];    for (int i = 0; i < V; i++)        visited[i] = false;    // Call the recursive helper function to store Topological    // Sort starting from all vertices one by one    for (int i = 0; i < V; i++)      if (visited[i] == false)        topologicalSortUtil(i, visited, Stack);    // Print contents of stack    while (Stack.empty() == false)    {        cout << Stack.top() << " ";        Stack.pop();    }}// Driver program to test above functionsint main(){    // Create a graph given in the above diagram    Graph g(6);    g.addEdge(5, 2);    g.addEdge(5, 0);    g.addEdge(4, 0);    g.addEdge(4, 1);    g.addEdge(2, 3);    g.addEdge(3, 1);    cout << "Following is a Topological Sort of the given graph n";    g.topologicalSort();    return 0;}