Prim算法

来源：互联网发布：彩虹岛知乎编辑：程序博客网时间：2024/05/01 04:30
#include <iostream>#include <cstring>#include <vector>#include <queue>using namespace std;const int INF = 0x3f3f3f3f;struct Edge {    int vertex, weight;};class Graph {private:    int n;    bool * visited;    vector<Edge> * edges;public:    int * dist;    Graph (int input_n) {        n = input_n;        edges = new vector<Edge>[n];        dist = new int[n];        visited = new bool[n];        memset(visited, false, n * sizeof(bool));        memset(dist, 0x3f, n * sizeof(int));    }    ~Graph() {        delete[] dist;        delete[] visited;        delete[] edges;    }    void insert(int x, int y, int weight) {        edges[x].push_back(Edge{y, weight});        edges[y].push_back(Edge{x, weight});    }    int prim(int v) {        int total_weight=0;        dist[v]=0;        for(int i=0;i<n;++i)        {           int min_dist=INF,min_vertex;           for(int j=0;j<n;++j)           {               if(!visited[j]&&dist[j]<min_dist)               {                  min_dist=dist[j];                  min_vertex=j;               }           }           total_weight+=min_dist;           visited[min_vertex]=1;            int ire=0;            for(;ire!=edges[min_vertex].size();++ire)            {                Edge j=edges[min_vertex][ire];                if (!visited[j.vertex]&&j.weight<dist[j.vertex]){                       dist[j.vertex]=j.weight;}            }        }        return total_weight;    }};int main() {    int n, m;    cin >> n >> m;    Graph g(n);    for (int i = 0; i < m; i++) {        int a, b, c;        cin >> a >> b >> c;        g.insert(a, b, c);    }    cout << g.prim(0) << endl;    return 0;}
适用于边较少，而顶点较多的情况
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