poj 1847( floyd && spfa )

http://poj.org/problem?id=1847

一个水题，用来熟悉熟悉spfa和floyd的。

题意：有m条的铁路，要从x,到y,

之后分别就是条铁路与其他铁路的交点。第一个输入的为有n个交点。之后第一个输入的点，当前铁路到这个点是不要转向的，也就是权值为0，其余的权值都为1，求从x到y的最短路，如果到不了输出-1

裸的floyd和spfa；

 #include <stdio.h>
 #include <string.h>
 #define inf 0x3f3f

 int graph[][];
 int m,n,x,y;

 void floyd()
 {
     int k,i,j;
     for( k =  ; k <= m ; k++ )
         for( i =  ; i <= m ; i++ )
             for( j =  ; j <= m ; j++)
                 if( graph[ i ][ j ] > graph[ i ][ k ] + graph[ k ][ j ] )
                     graph[ i ][ j ] = graph[ i ][ k ] + graph[ k ][ j ];
 }

 int main()
 {
    // freopen("in.txt","r",stdin);
     int tmp;
     while(scanf("%d%d%d",&m,&x,&y)!=EOF)
     {
         for( int i =  ; i <= m ; i++ )
             for( int j =  ; j <= m ; j++ )
                 if( i == j )
                     graph[ i ][ j ] = ;
                 else
                     graph[ i ][ j ] = inf;
         for( int i =  ; i <= m ; i++ )
         {
             scanf("%d",&n);
             for( int j =  ;j <= n ; j++ )
             {
                 scanf("%d",&tmp);
                 if( j ==  )
                     graph[ i ][ tmp ] = ;
                 else
                     graph[ i ][ tmp ] = ;
             }
         }
         floyd();
         if( graph[ x ][ y ] != inf)
             printf("%d\n",graph[ x ][ y ]);
         else
             printf("-1\n");
     }
     return ;
 }

floyd

 #include <stdio.h>
 #include <string.h>
 #include <queue>
 #define maxn 101
 #define inf 0x3f3f3f3f

 using namespace std;

 int m,x,n,y,pos,head[ maxn ];

 int ans , dist[ maxn ];

 bool vis[ maxn ];

 struct note {
     int v,w,next;
 }edge[maxn];

 void init()
 {
     pos = ;
     for(int i =  ;i <= n ; i++ ) dist[ i ] = inf;
     memset( head , - , sizeof( head ) );
     memset( vis , false ,sizeof( vis ) );
 }

 void add(int x,int v,int w)
 {
     edge[ pos ].v = v;
     edge[ pos ].w = w;
     edge[ pos ].next = head[ x ];
     head[ x ] = pos++;
 }

 void spfa()
 {
     queue<int >s;
     s.push(x);
     vis[ x ] = true;
     dist[ x ] = ;
     while(!s.empty())
     {
         int tmp = s.front();
         s.pop();
         vis [ tmp ] = false;
         for( int i = head[ tmp ] ; i != - ; i = edge[ i ].next )
         {
             if( dist[ edge[ i ].v ] > dist[ tmp ] + edge[ i ].w)
             {
                 dist[ edge[ i ].v ] = dist[ tmp ] + edge[ i ].w;
                 if( !vis[ edge[ i ].v ] )
                 {
                     s.push( edge[ i ].v );
                     vis[ edge[ i ].v ] =true;
                 }
             }

         }
     }
 }

 int main()
 {
   //  freopen("in.txt","r",stdin);
     while(~scanf("%d%d%d",&n,&x,&y))
     {
         init();
         int tmp;
         for(int j =  ; j <= n ; j++ )
         {
             scanf("%d",&m);
             for(int i =  ; i <= m ; i++ )
             {
                 scanf("%d",&tmp);
                 if( i ==  ) add( j , tmp , );
                 else add( j , tmp ,  );
             }
         }
         spfa();
         if( dist [ y ] == inf ) printf("-1\n");
         else printf("%d\n",dist[ y ]);
     }
     return ;
 }

spfa