Question

这是一个有效的Prim算法，采用了三个int。我的问题是我的边缘是字母，而不是数字。我似乎无法对其进行调试以使其与char（而不是int）一起使用，因此我转向你们。任何帮助，将不胜感激！

using namespace std;
# define INF 0x3f3f3f3f

// iPair ==>  Integer Pair
typedef pair<int, int> iPair;

// This class represents a directed graph using
// adjacency list representation
class Graph
{
    int V;    // No. of vertices

    // In a weighted graph, we need to store vertex
    // and weight pair for every edge
    list< pair<int, int> > *adj;

public:
    Graph(int V);  // Constructor

    // function to add an edge to graph
    void addEdge(int u, int v, int w);

    // Print MST using Prim's algorithm
    void primMST();
};

// Allocates memory for adjacency list
Graph::Graph(int V)
{
    this->V = V;
    adj = new list<iPair> [V];
}

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

// Prints shortest paths from src to all other vertices
void Graph::primMST()
{
    // Create a priority queue to store vertices that
// are being preinMST. This is weird syntax in C++.
// Refer below link for details of this syntax
// http://geeksquiz.com/implement-min-heap-using-stl/
priority_queue< iPair, vector <iPair> , greater<iPair> > pq;

int src = 0; // Taking vertex 0 as source

// Create a vector for keys and initialize all
// keys as infinite (INF)
vector<int> key(V, INF);

// To store parent array which in turn store MST
vector<int> parent(V, -1);

// To keep track of vertices included in MST
vector<bool> inMST(V, false);

// Insert source itself in priority queue and initialize
// its key as 0.
pq.push(make_pair(0, src));
key[src] = 0;

/* Looping till priority queue becomes empty */
while (!pq.empty())
{
    // The first vertex in pair is the minimum key
    // vertex, extract it from priority queue.
    // vertex label is stored in second of pair (it
    // has to be done this way to keep the vertices
    // sorted key (key must be first item
    // in pair)
    int u = pq.top().second;
    pq.pop();

    inMST[u] = true;  // Include vertex in MST

    // 'i' is used to get all adjacent vertices of a vertex
    list< pair<int, int> >::iterator i;
    for (i = adj[u].begin(); i != adj[u].end(); ++i)
    {
        // Get vertex label and weight of current adjacent
        // of u.
        int v = (*i).first;
        int weight = (*i).second;

        //  If v is not in MST and weight of (u,v) is smaller
        // than current key of v
        if (inMST[v] == false && key[v] > weight)
        {
            // Updating key of v
            key[v] = weight;
            pq.push(make_pair(key[v], v));
            parent[v] = u;
        }
    }
}

// Print edges of MST using parent array
for (int i = 1; i < V; ++i)
    printf("%d - %d\n", parent[i], i);
}

我尝试将typedef pair更改为<char, char>，并将*adj更改为<char, char>。问题出在函数addEdge上，使用list创建了我的图表。

Answer 1

您的代码似乎已被from here使用。当您在线运行代码时，一切正常。您可以将他们的版本与他们的版本进行比较，看看出了什么问题。

C ++实现中带字母的Prim算法

1 个答案: