USACO chapter 2 section 2.4 Overfencing

USACO chapter 2 section 2.4 Overfencing

USER: tian tianbing [tbbd4261]
TASK: maze1
LANG: C++

Compiling...
Compile: OK

Executing...
   Test 1: TEST OK [0.011 secs, 3052 KB]
   Test 2: TEST OK [0.000 secs, 3052 KB]
   Test 3: TEST OK [0.000 secs, 3052 KB]
   Test 4: TEST OK [0.000 secs, 3052 KB]
   Test 5: TEST OK [0.011 secs, 3052 KB]
   Test 6: TEST OK [0.000 secs, 3088 KB]
   Test 7: TEST OK [0.022 secs, 3052 KB]
   Test 8: TEST OK [0.000 secs, 3052 KB]
   Test 9: TEST OK [0.011 secs, 3052 KB]
   Test 10: TEST OK [0.151 secs, 3052 KB]

All tests OK.

Your program ('maze1') produced all correct answers!  This is your
submission #2 for this problem.  Congratulations!

DFS从两个入口各搜索一次，更新即可。

先写了一个代码，太乱，花了不少时间，后来重写了，要注意的代码的整洁。

  
  
  
  

   
   
   
   /*
   
   
   
   
ID:tbbd4261
PROG:maze1
LANG:C++

   
   
   
   */
   
   
   
   

#include
   
   
   
   <
   
   
   
   fstream
   
   
   
   >
   
   
   
   

   
   
   
   using
   
   
   
    
   
   
   
   namespace
   
   
   
    std;
ifstream fin(
   
   
   
   "
   
   
   
   maze1.in
   
   
   
   "
   
   
   
   );
ofstream fout(
   
   
   
   "
   
   
   
   maze1.out
   
   
   
   "
   
   
   
   );

   
   
   
   char
   
   
   
    wall[
   
   
   
   205
   
   
   
   ][
   
   
   
   80
   
   
   
   ]
   
   
   
   =
   
   
   
   {
   
   
   
   0
   
   
   
   };

   
   
   
   int
   
   
   
    step[
   
   
   
   105
   
   
   
   ][
   
   
   
   40
   
   
   
   ]
   
   
   
   =
   
   
   
   {
   
   
   
   0
   
   
   
   };

   
   
   
   char
   
   
   
    ch;

   
   
   
   int
   
   
   
    x1
   
   
   
   =
   
   
   
   0
   
   
   
   ,y1
   
   
   
   =
   
   
   
   0
   
   
   
   ,x2
   
   
   
   =
   
   
   
   0
   
   
   
   ,y2
   
   
   
   =
   
   
   
   0
   
   
   
   ,i,j,w,h;

   
   
   
   int
   
   
   
    dx[
   
   
   
   4
   
   
   
   ]
   
   
   
   =
   
   
   
   {
   
   
   
   -
   
   
   
   1
   
   
   
   ,
   
   
   
   1
   
   
   
   ,
   
   
   
   0
   
   
   
   ,
   
   
   
   0
   
   
   
   },dy[
   
   
   
   4
   
   
   
   ]
   
   
   
   =
   
   
   
   {
   
   
   
   0
   
   
   
   ,
   
   
   
   0
   
   
   
   ,
   
   
   
   -
   
   
   
   1
   
   
   
   ,
   
   
   
   1
   
   
   
   };



   
   
   
   void
   
   
   
    input()
{
     fin
   
   
   
   >>
   
   
   
   w
   
   
   
   >>
   
   
   
   h;  
     fin.
   
   
   
   get
   
   
   
   ();
     
   
   
   
   for
   
   
   
   (i
   
   
   
   =
   
   
   
   1
   
   
   
   ; i
   
   
   
   <=
   
   
   
   2
   
   
   
   *
   
   
   
   h
   
   
   
   +
   
   
   
   1
   
   
   
   ; i
   
   
   
   ++
   
   
   
   )
     {
        
   
   
   
   for
   
   
   
   (j
   
   
   
   =
   
   
   
   1
   
   
   
   ; j
   
   
   
   <=
   
   
   
   2
   
   
   
   *
   
   
   
   w
   
   
   
   +
   
   
   
   1
   
   
   
   ; j
   
   
   
   ++
   
   
   
   )
              {
                   fin.
   
   
   
   get
   
   
   
   (ch); wall[i][j]
   
   
   
   =
   
   
   
   ch;
                   
   
   
   
   if
   
   
   
   ((i
   
   
   
   ==
   
   
   
   1
   
   
   
   ||
   
   
   
   i
   
   
   
   ==
   
   
   
   2
   
   
   
   *
   
   
   
   h
   
   
   
   +
   
   
   
   1
   
   
   
   ||
   
   
   
   j
   
   
   
   ==
   
   
   
   1
   
   
   
   ||
   
   
   
   j
   
   
   
   ==
   
   
   
   2
   
   
   
   *
   
   
   
   w
   
   
   
   +
   
   
   
   1
   
   
   
   )
   
   
   
   &&
   
   
   
   ch
   
   
   
   ==
   
   
   
   '
   
   
   
    
   
   
   
   '
   
   
   
   )
                   {
                             
   
   
   
   if
   
   
   
   (
   
   
   
   !
   
   
   
   x1){ x1
   
   
   
   =
   
   
   
   i; y1
   
   
   
   =
   
   
   
   j; }
                             
   
   
   
   else
   
   
   
    {x2
   
   
   
   =
   
   
   
   i; y2
   
   
   
   =
   
   
   
   j; }
                   } 
              }
        fin.
   
   
   
   get
   
   
   
   ();
     }
}



   
   
   
   bool
   
   
   
    valid(
   
   
   
   int
   
   
   
    i, 
   
   
   
   int
   
   
   
    j)
{ 
   
   
   
   return
   
   
   
    i
   
   
   
   >=
   
   
   
   2
   
   
   
   &&
   
   
   
   i
   
   
   
   <=
   
   
   
   2
   
   
   
   *
   
   
   
   h
   
   
   
   &&
   
   
   
   j
   
   
   
   >=
   
   
   
   2
   
   
   
   &&
   
   
   
   j
   
   
   
   <=
   
   
   
   2
   
   
   
   *
   
   
   
   w
   
   
   
   &&
   
   
   
   (i
   
   
   
   %
   
   
   
   2
   
   
   
   ==
   
   
   
   0
   
   
   
   )
   
   
   
   &&
   
   
   
   (j
   
   
   
   %
   
   
   
   2
   
   
   
   ==
   
   
   
   0
   
   
   
   ) ; }


   
   
   
   bool
   
   
   
    valid2(
   
   
   
   int
   
   
   
    i, 
   
   
   
   int
   
   
   
    j){
   
   
   
   return
   
   
   
    i
   
   
   
   >=
   
   
   
   1
   
   
   
   &&
   
   
   
   i
   
   
   
   <=
   
   
   
   h
   
   
   
   &&
   
   
   
   j
   
   
   
   >=
   
   
   
   1
   
   
   
   &&
   
   
   
   j
   
   
   
   <=
   
   
   
   w; }


   
   
   
   void
   
   
   
    deal(
   
   
   
   int
   
   
   
    
   
   
   
   &
   
   
   
   x, 
   
   
   
   int
   
   
   
    
   
   
   
   &
   
   
   
   y)
{
     
   
   
   
   for
   
   
   
   ( i
   
   
   
   =
   
   
   
   0
   
   
   
   ; i
   
   
   
   <
   
   
   
   4
   
   
   
   ; i
   
   
   
   ++
   
   
   
    )
         
   
   
   
   if
   
   
   
   (valid(x
   
   
   
   +
   
   
   
   dx[i],y
   
   
   
   +
   
   
   
   dy[i]))
         { x
   
   
   
   =
   
   
   
   x
   
   
   
   +
   
   
   
   dx[i]; y
   
   
   
   =
   
   
   
   y
   
   
   
   +
   
   
   
   dy[i]; }
     x
   
   
   
   /=
   
   
   
   2
   
   
   
   ; y
   
   
   
   /=
   
   
   
   2
   
   
   
   ;
}


   
   
   
   void
   
   
   
    dfs(
   
   
   
   int
   
   
   
    i, 
   
   
   
   int
   
   
   
    j)
{
      
   
   
   
   for
   
   
   
   (
   
   
   
   int
   
   
   
    k
   
   
   
   =
   
   
   
   0
   
   
   
   ; k
   
   
   
   <
   
   
   
   4
   
   
   
   ; k
   
   
   
   ++
   
   
   
   )
          
   
   
   
   if
   
   
   
   (valid2(i
   
   
   
   +
   
   
   
   dx[k],j
   
   
   
   +
   
   
   
   dy[k])
   
   
   
   &&
   
   
   
   wall[
   
   
   
   2
   
   
   
   *
   
   
   
   i
   
   
   
   +
   
   
   
   dx[k]][j
   
   
   
   *
   
   
   
   2
   
   
   
   +
   
   
   
   dy[k]]
   
   
   
   ==
   
   
   
   '
   
   
   
    
   
   
   
   '
   
   
   
   )
               
   
   
   
   if
   
   
   
   ((step[i
   
   
   
   +
   
   
   
   dx[k]][j
   
   
   
   +
   
   
   
   dy[k]]
   
   
   
   >
   
   
   
   step[i][j]
   
   
   
   +
   
   
   
   1
   
   
   
   )
   
   
   
   ||
   
   
   
   step[i
   
   
   
   +
   
   
   
   dx[k]][j
   
   
   
   +
   
   
   
   dy[k]]
   
   
   
   ==
   
   
   
   0
   
   
   
   )      
               {  step[i
   
   
   
   +
   
   
   
   dx[k]][j
   
   
   
   +
   
   
   
   dy[k]]
   
   
   
   =
   
   
   
   step[i][j]
   
   
   
   +
   
   
   
   1
   
   
   
   ; dfs(i
   
   
   
   +
   
   
   
   dx[k],j
   
   
   
   +
   
   
   
   dy[k]); }
}

   
   
   
   int
   
   
   
    main()
{
    input();
    deal(x1,y1);
    deal(x2,y2);
    step[x1][y1]
   
   
   
   =
   
   
   
   1
   
   
   
   ;
    step[x2][y2]
   
   
   
   =
   
   
   
   1
   
   
   
   ;
    dfs(x1,y1);
    dfs(x2,y2);
    
   
   
   
   int
   
   
   
    max
   
   
   
   =
   
   
   
   1
   
   
   
   ;
    
   
   
   
   for
   
   
   
   (i
   
   
   
   =
   
   
   
   1
   
   
   
   ; i
   
   
   
   <=
   
   
   
   h; i
   
   
   
   ++
   
   
   
   )
    
   
   
   
   for
   
   
   
   (j
   
   
   
   =
   
   
   
   1
   
   
   
   ; j
   
   
   
   <=
   
   
   
   w; j
   
   
   
   ++
   
   
   
   )
       
   
   
   
   if
   
   
   
   (step[i][j]
   
   
   
   >
   
   
   
   max)max
   
   
   
   =
   
   
   
   step[i][j];
    fout
   
   
   
   <<
   
   
   
   max
   
   
   
   <<
   
   
   
   endl;   
    
   
   
   
   return
   
   
   
    
   
   
   
   0
   
   
   
   ;
}