hdu1874(畅通工程续)

http://acm.hdu.edu.cn/showproblem.php?pid=1874

View Code

   
     

    
      #include
    
      <
    
      iostream
    
      >
    
      

    
      #define
    
       _max 9999999
    
      

    
      #define
    
       M 201
    
      

    
      using
    
       
    
      namespace
    
       std;

    
      int
    
       map[M][M];

    
      int
    
       visit[M];

    
      int
    
       dir[M];

    
      int
    
       n , m ;

    
      int
    
       a , b , c ;

    
      int
    
       len;

    
      void
    
       Init(
    
      int
    
       n)
{
 
    
      int
    
       i,j;
 
    
      for
    
      (i 
    
      =
    
       
    
      0
    
       ; i 
    
      <
    
      n ; i
    
      ++
    
      )
 {
 
    
      for
    
      (j
    
      =
    
      0
    
       ; j 
    
      <
    
      n; j
    
      ++
    
      )
 map[i][j] 
    
      =
    
       _max;
 }
}

    
      void
    
       DJ(
    
      int
    
       v)
{
 
    
      int
    
       i,j,p,k ,_min;
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <=
    
      n;i
    
      ++
    
      )
 dir[i]
    
      =
    
      map[v][i];
 dir[v]
    
      =
    
      0
    
      ;
 visit[v]
    
      =
    
      true
    
      ;
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <=
    
      n;i
    
      ++
    
      )
 {
 _min
    
      =
    
      _max;
 
    
      for
    
      (j
    
      =
    
      0
    
      ;j
    
      <
    
      n;j
    
      ++
    
      )
 {
 
    
      if
    
      (
    
      !
    
      visit[j] 
    
      &&
    
       _min
    
      >
    
      dir[j])
 {
 _min 
    
      =
    
       dir[j];
 k 
    
      =
    
       j;
 }
 }
 visit[k] 
    
      =
    
       
    
      true
    
       ;
 
    
      for
    
      ( p
    
      =
    
      0
    
       ; p
    
      <
    
      n; p
    
      ++
    
      )
 {
 
    
      if
    
      (
    
      !
    
      visit[p] 
    
      &&
    
       dir[p]
    
      >
    
      dir[k] 
    
      +
    
       map[k][p])
 {
 dir[p] 
    
      =
    
       dir[k] 
    
      +
    
       map[k][p];
 }
 }
 }
}

    
      int
    
       main()
{
 
 
    
      while
    
      (cin
    
      >>
    
      n
    
      >>
    
      m)
 {
 Init(n);
 
    
      int
    
       i;
 
    
      int
    
       s,e;
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <
    
      m;i
    
      ++
    
      )
 {
 cin
    
      >>
    
      a
    
      >>
    
      b
    
      >>
    
      c;
 
    
      if
    
      (map[a][b]
    
      >
    
      c) map[a][b] 
    
      =
    
       map[b][a] 
    
      =
    
       c;
 
 }
 memset(visit , 
    
      false
    
       , 
    
      sizeof
    
      (visit));
 cin
    
      >>
    
      s
    
      >>
    
      e;
 DJ(s);
 
    
      if
    
      (dir[e]
    
      <
    
      _max)cout
    
      <<
    
      dir[e]
    
      <<
    
      endl;
 
    
      else
    
       cout
    
      <<
    
      "
    
      -1
    
      "
    
      <<
    
      endl;
 }
 
    
      return
    
       
    
      0
    
      ;
 
}