使用pthreads实现最短路径算法并行化程序代码

下面是使用pthreads实现最短路径算法的并行化程序代码的一个例子：

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

#define MAX_NODES 100
#define INF 99999

int graph[MAX_NODES][MAX_NODES];
int dist[MAX_NODES];
int num_nodes, num_threads;

pthread_mutex_t mutex;

struct ThreadData {
    int start_node;
};

void* dijkstra(void* arg) {
    struct ThreadData* data = (struct ThreadData*)arg;
    int start_node = data->start_node;

    // 初始化距离数组和已访问数组
    for (int i = 0; i < num_nodes; i++) {
        dist[i] = INF;
    }
    dist[start_node] = 0;

    int visited[MAX_NODES] = {0};

    for (int count = 0; count < num_nodes - 1; count++) {
        int min_dist = INF;
        int min_index;

        // 找到当前未访问的节点中距离最小的节点
        for (int i = 0; i < num_nodes; i++) {
            if (!visited[i] && dist[i] < min_dist) {
                min_dist = dist[i];
                min_index = i;
            }
        }

        // 标记该节点为已访问
        visited[min_index] = 1;

        // 更新与该节点相邻节点的距离
        for (int i = 0; i < num_nodes; i++) {
            if (!visited[i] && graph[min_index][i] && dist[min_index] != INF && dist[min_index] + graph[min_index][i] < dist[i]) {
                dist[i] = dist[min_index] + graph[min_index][i];
            }
        }
    }

    pthread_mutex_lock(&mutex);
    printf("Thread %d: shortest distances from node %d:\n", start_node, start_node);
    for (int i = 0; i < num_nodes; i++) {
        printf("%d -> %d: %d\n", start_node, i, dist[i]);
    }
    pthread_mutex_unlock(&mutex);

    pthread_exit(NULL);
}

int main() {
    // 读取图数据和线程数量
    printf("Enter the number of nodes: ");
    scanf("%d", &num_nodes);

    printf("Enter the adjacency matrix:\n");
    for (int i = 0; i < num_nodes; i++) {
        for (int j = 0; j < num_nodes; j++) {
            scanf("%d", &graph[i][j]);
        }
    }

    printf("Enter the number of threads: ");
    scanf("%d", &num_threads);

    // 创建线程并运行最短路径算法
    pthread_t threads[num_threads];
    struct ThreadData thread_data[num_threads];

    pthread_mutex_init(&mutex, NULL);

    for (int i = 0; i < num_threads; i++) {
        thread_data[i].start_node = i;
        pthread_create(&threads[i], NULL, dijkstra, (void*)&thread_data[i]);
    }

    for (int i = 0; i < num_threads; i++) {
        pthread_join(threads[i], NULL);
    }

    pthread_mutex_destroy(&mutex);

    return 0;
}

请确保在编译和运行此代码之前已经安装了pthreads库