C++ Dijkstra算法如何并行化

发布时间:2024-07-25 17:27:18

阅读量:88

在C++中，Dijkstra算法可以通过使用并行化技术来加速处理过程。一种常见的方法是使用OpenMP库来实现并行化。以下是一个简单的示例代码，展示了如何在C++中使用OpenMP并行化Dijkstra算法：

#include 
#include 
#include 
#include 

#define INF std::numeric_limits::max()

int dijkstra(const std::vectorint>>& graph, int source, int destination) {
    int num_vertices = graph.size();
    std::vector<int> distance(num_vertices, INF);
    std::vector<bool> visited(num_vertices, false);

    distance[source] = 0;
    
#pragma omp parallel for
    for (int i = 0; i < num class="hljs-type">int u = -1;
        int min_distance = INF;
        
        // Find the vertex with the minimum distance from the source
        for (int j = 0; j < num class="hljs-keyword">if (!visited[j] && distance[j] < min xss=removed xss=removed class="hljs-keyword">if (u == -1) break; // No more vertices to visit
        
        visited[u] = true;
        
        // Update the distances of neighboring vertices
#pragma omp parallel for
        for (int v = 0; v < num class="hljs-keyword">if (!visited[v] && graph[u][v] && distance[u] != INF && distance[u] + graph[u][v] < distance xss=removed class="hljs-keyword">return distance[destination];
}

int main() {
    std::vectorint>> graph = {
        {0, 4, 0, 0, 0, 0, 0, 8, 0},
        {4, 0, 8, 0, 0, 0, 0, 11, 0},
        {0, 8, 0, 7, 0, 4, 0, 0, 2},
        {0, 0, 7, 0, 9, 14, 0, 0, 0},
        {0, 0, 0, 9, 0, 10, 0, 0, 0},
        {0, 0, 4, 14, 10, 0, 2, 0, 0},
        {0, 0, 0, 0, 0, 2, 0, 1, 6},
        {8, 11, 0, 0, 0, 0, 1, 0, 7},
        {0, 0, 2, 0, 0, 0, 6, 7, 0}
    };

    int source = 0;
    int destination = 4;
    int shortest_path = dijkstra(graph, source, destination);

    std::cout << "Shortest path from vertex " << source class="hljs-string">" to vertex " << destination class="hljs-string">" is " << shortest class="hljs-keyword">return 0;
}