写一段代码一个无向图的BFS算法并用C语言实现

以下是一个用C语言实现的无向图BFS算法的代码段：

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

#define MAX_VERTICES 100

typedef struct node {
    int vertex;
    struct node* next;
} node;

typedef struct graph {
    node* vertices[MAX_VERTICES];
    int visited[MAX_VERTICES];
    int num_vertices;
} graph;

void add_edge(graph* g, int src, int dest) {
    node* new_node = (node*)malloc(sizeof(node));
    new_node->vertex = dest;
    new_node->next = g->vertices[src];
    g->vertices[src] = new_node;
}

void bfs(graph* g, int start) {
    int queue[MAX_VERTICES];
    int front = 0, rear = 0;

    queue[rear++] = start;
    g->visited[start] = 1;

    while (front < rear) {
        int current = queue[front++];
        printf("%d ", current);

        node* temp = g->vertices[current];
        while (temp) {
            int adj_vertex = temp->vertex;
            if (!g->visited[adj_vertex]) {
                queue[rear++] = adj_vertex;
                g->visited[adj_vertex] = 1;
            }
            temp = temp->next;
        }
    }
}

int main() {
    graph* g = (graph*)malloc(sizeof(graph));
    g->num_vertices = 6;
    for (int i = 0; i < g->num_vertices; i++) {
        g->vertices[i] = NULL;
        g->visited[i] = 0;
    }

    add_edge(g, 0, 1);
    add_edge(g, 0, 2);
    add_edge(g, 1, 2);
    add_edge(g, 2, 0);
    add_edge(g, 2, 3);
    add_edge(g, 3, 3);

    printf("BFS traversal starting from vertex 2: ");
    bfs(g, 2);

    return 0;
}

这段代码实现了一个无向图的BFS算法，可以在main函数中添加更多的add_edge函数调用来构建不同的图，并在bfs函数中指定不同的起始顶点来进行遍历。