1 #include<stdio.h>
  2 #include<string.h>
  3 #include <iostream>
  4 #include<algorithm>
  5 using namespace std;
  6 #define MVNum 100
  7 int vis[MVNum];
  8 typedef struct ArcNode
  9 {
 10     int adjvex;
 11     int info;
 12     struct ArcNode *nextarc;
 13 } ArcNode;
 
 14 typedef struct VNode
 15 {
 16     char data;
 17     ArcNode *firstarc;
 18 } VNode, AdjList[MVNum];
 19 typedef struct
 20 {
 21     AdjList vertices;
 22     int vexnum,arcnum;
 23 } ALGraph;
 24 
 25 typedef struct
 26 {
 27     int *base;//儲存空間的基地址
 28     int front;//頭指標
 29     int rear;//尾指標
 30
 
 } SqQueue;
 31 void InitQueue(SqQueue &Q) //初始化
 32 {
 33     Q.base=new int[MVNum];
 34     if(!Q.base)
 35         printf("儲存分配失敗\n");
 36     Q.front=Q.rear=0;
 37 }
 38 int QueueEmpty(SqQueue Q) //求迴圈佇列是否為空
 39 {
 40     if(Q.front==Q.rear)
 41         return 1;
 42     else
 43         return 0;
 
 44 }
 45 int EnQueue(SqQueue &Q,int e) //入隊
 46 {
 47     if((Q.rear+1)%MVNum==Q.front)//隊滿
 48         return 0;
 49     Q.base[Q.rear]=e;
 50     Q.rear=(Q.rear+1)%MVNum;
 51     return 1;
 52 }
 53 int DeQueue(SqQueue &Q,int &e) //出隊
 54 {
 55     if(Q.front==Q.rear)//隊滿
 56         return 0;
 57     e=Q.base[Q.front];
 58     Q.front=(Q.front+1)%MVNum;
 59     return 1;
 60 }
 61 
 62 int LocateVex(ALGraph &G,char v)//找到v在鄰接表G中的位置
 63 {
 64     for(int i=0; i<G.vexnum; i++)
 65     {
 66         if(G.vertices[i].data==v)
 67             return i;
 68     }
 69     return -1;
 70 }
 71 void  CreateALGraph(ALGraph &G)
 72 {
 73     int i,j,k,v;
 74     char v1,v2;
 75     ArcNode *p1,*p2;
 76     scanf("%d%d",&G.vexnum,&G.arcnum);
 77     for(v = 0; v < G.vexnum; v++)
 78     {
 79         scanf("%s",&G.vertices[v].data);
 80         G.vertices[v].firstarc=NULL;
 81     }
 82     getchar();
 83     for(k = 0; k < G.arcnum; k++)
 84     {
 85         scanf("%c %c",&v1,&v2);
 86         getchar();
 87         i=LocateVex(G,v1);
 88         j=LocateVex(G,v2);
 89         p1=new ArcNode;
 90         p1->adjvex=j;
 91         p1->nextarc=G.vertices[i].firstarc;
 92         G.vertices[i].firstarc=p1;
 93 
 94         p2=new ArcNode;
 95         p2->adjvex=i;
 96         p2->nextarc=G.vertices[j].firstarc;
 97         G.vertices[j].firstarc=p2;
 98     }
 99 }
100 
101 void BFS(ALGraph G,int v)
102 {
103     SqQueue Q;
104     int u,w;
105     ArcNode *p;
106     printf("%c",v+'A');
107     vis[v]=1;
108     InitQueue(Q);
109     EnQueue(Q,v);
110     while(!QueueEmpty(Q))
111     {
112         DeQueue(Q,u);
113         p=G.vertices[u].firstarc;
114       
115         while(p!=NULL)
116         {
117             w=p->adjvex;
118             if(!vis[w])
119             {
120                 printf("%c",w+'A');
121                 vis[w]=1;
122                 EnQueue(Q,w);
123             }
124             p=p->nextarc;
125         }
126     }
127 }
128 int main(void)
129 {
130     ALGraph G;
131     memset(vis,0,sizeof(vis));
132     CreateALGraph(G);
133     BFS(G,0);
134     return 0;
135 }

輸入：

8 9
A B C D E F G H
A B
B D
B E
E F
D F
A C
C G
C H
G H

輸出：

ACBHGEDF

鄰接表建立為：

A->C->B
B->E->D->A
C->H->G->A
D->F->B
E->F->B
F->D->E
G->H->C
H->G->C