无权无向图的邻接矩阵的BFS简单算法实现

#define  MAX_VEX 20
//#define  INFINITY 65535
#define  INFINITY 0

class Graph
{

public:
 Graph();
 ~Graph(){};
 
 int FirstVex(int i);
 int NextVex(int i , int j);
 void BFS_Graph(int start,int end);

 

public:
 int vexs[MAX_VEX];
 int arcs[MAX_VEX][MAX_VEX];
 int vexnum,arcnum;
 int pa[MAX_VEX];
};

 
Graph::Graph()
{
 int i ;  
 int ch1, ch2;  
 
 memset(arcs,INFINITY,sizeof(arcs));
 memset(pa,0,sizeof(pa));

 printf("Enter vexnum arcnum: ");  
 scanf("%d,%d", &vexnum, &arcnum);  
 getchar();  
  
 printf("Enter %d vexnum.../n", vexnum);  
 for(i=1; i<=vexnum; i++)  
 {  
  printf("vex %d: ", i);  
  scanf("%d", &vexs[i]);  
  getchar();  
 }  
 printf("Enter %d arcnum.../n", arcnum);  
 for(i=1; i<=arcnum; i++)  
 {  
  printf("arc %d: ", i);  
  scanf("%d,%d", &ch1, &ch2);  
  getchar();  
  arcs[ch1][ch2]=arcs[ch2][ch1]=1;  
 }  
 
}

int Graph::FirstVex(int sceneid)
{
 
 if ( sceneid > 0 && sceneid <=  MAX_VEX)
 {
  for (int k = 1 ;  k<= vexnum ; k++ )
  {
   if ( arcs[sceneid][k] != INFINITY )
   {
    return k;
   }
  }
 }
  
 return -1;
}

//return  arcs[sceneid][k] != INFINITY ? k : -1;

int Graph::NextVex(int i , int j)
{
 int k;

 if ( i> 0 && i <= MAX_VEX && j > 0 && j<= MAX_VEX )
 {
  for (k = j+1 ; k<= vexnum ; k ++ )
  {
   if ( arcs[i][k] != INFINITY )
   {
    return k;
   }
  }
 }
 return -1;
}

void Graph::BFS_Graph(int start,int end)
{
 int visited[MAX_VEX];
 int pa[MAX_VEX];
 int parent = start;
 int k;
 int path[MAX_VEX];
 int pathlen = 0;
 
 
 memset(path,0,sizeof(path));

 queue<int>q;
 memset(visited,0,sizeof(visited));
 memset(pa,0,sizeof(pa)); 
 
 visited[start]= 1;
 pa[start] = -1;
 q.push(start);
 
 while ( !q.empty())
 {
  k = q.front();
  parent = k ;
  q.pop();
  for(int j=FirstVex( k); j>=1; j=NextVex( k, j))  
   if(!visited[j])  
   {  
    visited[j]=1;  
    pa[ vexs[j] ]= parent;  
    if ( vexs[j] == end)
    {
     cout<<"找到目标路径"<<endl;
     break;
    }
   
    q.push( j );  
   }  
 }

 cout<<"路径如下"<<endl;
 parent = end;  
 
 while (  parent != -1 )
 {
  path[pathlen++] =parent;
  cout<<parent<<"--";
  parent = pa[parent];
 }
 cout<<endl;
 cout<<"path 如下"<<endl;
 
 pathlen = 0 ;
 while ( path[pathlen] != 0 )
 {
  cout<<path[pathlen++]<<"--";
 }
 
}

int _tmain()
{
 Graph gGraph;  
 gGraph.BFS_Graph(3,4);

 return 0;
}