typedef struct{ int v; int parent; }QUEUE1; int BFSA(AdjGraph *G,int u,int v){ ArcNode *p; SqQueue *qu; InitQueue(qu); int visited[MAXV]; for(int i=0;i<G->n;i++){ visited[i]=0; } QUEUE1 elem; elem.v=u; elem.parent=-1; enQueue(qu,v); while(!QueueEmpty(qu)){ deQueue(qu,&v); if(elem.v==v){ while(!QueueEmpty(qu)){ deQueue(qu,&v); } break; } p=G->adjlist[elem.v].firstarc; while(p!=NULL){ int w=p->adjvex; if(visited[w]==0){ visited[w]=1; QUEUE1 new_v; new_v.v=w; new_v.parent=elem.v; enQueue(qu,w); } p=p->nextarc; } } if(elem.v!=v){ printf("不存在从%d到%d的路径\n",u,v); return -1; }else{ int len=0; while(elem.parent!=-1){ len++; elem=getQueueElem(qu,elem.parent); } printf("从%d到%d的最短路径长度为：%d\n",u,v,len); return len; } }加入getQueueElem函数

在上述代码中，需要加入 `getQueueElem` 函数，用于根据队列中元素的 `parent` 属性找到其对应的元素。可以按照以下方式实现该函数：

QUEUE1 getQueueElem(SqQueue *qu, int parent) {
    QUEUE1 elem;
    int i = qu->front;
    while (i != qu->rear) {
        i = (i + 1) % MAXSIZE;
        if (qu->data[i].v == parent) {
            elem = qu->data[i];
            break;
        }
    }
    return elem;
}

在使用该函数时，需要将 `qu` 传入 `getQueueElem` 函数中，如下所示：

elem = getQueueElem(qu, elem.parent);

综上所述，修改后的代码如下所示：

typedef struct {
    int v;
    int parent;
} QUEUE1;

int BFSA(AdjGraph *G, int u, int v) {
    SqQueue *qu;
    InitQueue(qu);

    int visited[MAXV];
    for (int i = 0; i < G->n; i++) {
        visited[i] = 0;
    }

    QUEUE1 elem;
    elem.v = u;
    elem.parent = -1;
    enQueue(qu, elem);

    while (!QueueEmpty(qu)) {
        deQueue(qu, &elem);
        if (elem.v == v) {
            break;
        }
        ArcNode *p;
        p = G->adjlist[elem.v].firstarc;
        while (p != NULL) {
            int w = p->adjvex;
            if (visited[w] == 0) {
                visited[w] = 1;
                QUEUE1 new_v;
                new_v.v = w;
                new_v.parent = elem.v;
                enQueue(qu, new_v);
            }
            p = p->nextarc;
        }
    }

    if (elem.v != v) {
        printf("不存在从%d到%d的路径\n", u, v);
        return -1;
    } else {
        int len = 0;
        while (elem.parent != -1) {
            len++;
            elem = getQueueElem(qu, elem.parent);
        }
        printf("从%d到%d的最短路径长度为：%d\n", u, v, len);
        return len;
    }

    DestroyQueue(qu);
}

QUEUE1 getQueueElem(SqQueue *qu, int parent) {
    QUEUE1 elem;
    int i = qu->front;
    while (i != qu->rear) {
        i = (i + 1) % MAXSIZE;
        if (qu->data[i].v == parent) {
            elem = qu->data[i];
            break;
        }
    }
    return elem;
}