数据结构 — 图 之 广度优先遍历

【描述】：  图的bfs

【输入】：

8
1 2 -1
0 3 4 -1
0 5 6 -1
1 7 -1
1 7 -1
2 7 -1
2 7 -1
3 4 5 6 -1

【输出】：

0 1 2 3 4 5 6 7

/*
 *图的广度优先遍历
 *1.链式队列（链表的头节点中存数据、节点的尾插法、头节点的删除）
 *2.bfs 

8 
1 2 -1 
0 3 4 -1 
0 5 6 -1 
1 7 -1 
1 7 -1 
2 7 -1 
2 7 -1 
3 4 5 6 -1 
 */

#include<iostream>
#include<memory.h>
using namespace std;

/* 宏定义 */
#define MAX_NUM 50
#define ElementType int

/* 定义动态链式队列节点 */
typedef struct QueueNode{
    ElementType data;
    struct QueueNode *next;
}QueueNode,*QueuePointer;

/* 邻接表表节点 */
typedef struct TableNode{
    ElementType vertex;
    struct TableNode *next;
}TableNode,*TablePointer;

/* 头节点数组 */
TablePointer graph[MAX_NUM];

/* 定义visited数组 */
bool visited[MAX_NUM];

/* 顶点数 */
int vertices;

/*
 * 动态链式队列
 * 1.addq -> 入队
 * 2.deleteq -> 出队
 */
/*在链式队列的队尾插入元素*/
void addq(QueuePointer &front, QueuePointer &rear, ElementType item){
    QueuePointer temp = new QueueNode;
    temp->data = item;
    temp->next = NULL;

    //插入
    if(front){
        rear->next = temp;
    }else{
        front = temp;
    }
    rear = temp;
}

/*从链式队列的头部出队*/
ElementType deleteq(QueuePointer &front){
    QueuePointer temp = front;
    ElementType item;

    //出队
    item = temp->data;
    front = temp->next;
    delete temp;
    return item;
}

/*
 * 邻接表存储的图
 * 1.创建图
 * 2.bfs
 */
/*创建*/
void CreateGraph(){  
    ElementType ch;  
    TablePointer pnew,qnode;  
    pnew = qnode = NULL;  
  
    for(int i = 0; i < vertices; i++){  
        cin>>ch;  
        if(ch == -1) continue; /*当ch 为-1是结束该vertex的创建*/  
        //链表的头节点  
        pnew = new TableNode;  
        pnew->vertex = ch;  
        pnew->next = NULL;  
        //将头节点存入 头节点数组  
        graph[i] = pnew;  
        //尾插法创建链表  
        cin>>ch;  
        while(ch != -1){  
            //申请内存、处理数据域、处理指针域  
            qnode = new TableNode;  
            qnode->vertex = ch;  
            qnode->next =NULL;  
            //插入  
            pnew->next = qnode;  
            //更新尾指针  
            pnew = qnode;  
            cin>>ch;  
        }  
    }  
}

/*bfs*/
void bfs(ElementType v){
    TablePointer w;
    QueuePointer front, rear;
    front = rear = NULL;

    //将第一个节点输入、标记、进队
    cout<<v<<endl;
    visited[v] = true;
    addq(front, rear, v);

    //访问队列中的节点、访问与其相邻的节点、已经被visited的节点将不再访问
    while(front){
        v = deleteq(front);
	//扫vertex v 的链表
        for(w = graph[v]; w; w=w->next){
            if(!visited[w->vertex]){
                cout<<w->vertex<<" ";
		visited[w->vertex] = true;
                addq(front, rear, w->vertex);
            }
	}
    }
	cout<<endl;
}

int main(){  
  
    memset(visited,false,sizeof(visited));  
  
    cout<<"输入顶点数"<<endl;  
    cin>>vertices;  
  
    CreateGraph();  
    cout<<"广度优先遍历"<<endl;  
    bfs(0);  

    return 0;  
}  

【运行结果】：