poj3009

简单题

View Code

   
     

    
      #include 
    
      <
    
      iostream
    
      >
    
      
#include 
    
      <
    
      cstdio
    
      >
    
      
#include 
    
      <
    
      cstdlib
    
      >
    
      
#include 
    
      <
    
      cstring
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      #define
    
       maxn 25
    
      


    
      struct
    
       Point
{
 
    
      int
    
       x, y;
} s, e;


    
      bool
    
       map[maxn][maxn];

    
      int
    
       n, m, ans;

    
      bool
    
       found;

    
      int
    
       dir[
    
      4
    
      ][
    
      2
    
      ] 
    
      =
    
      
{
{ 
    
      0
    
      , 
    
      1
    
       },
{ 
    
      1
    
      , 
    
      0
    
       },
{ 
    
      0
    
      , 
    
      -
    
      1
    
       },
{ 
    
      -
    
      1
    
      , 
    
      0
    
       } };


    
      void
    
       input()
{
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 
    
      for
    
       (
    
      int
    
       j 
    
      =
    
       
    
      0
    
      ; j 
    
      <
    
       m; j
    
      ++
    
      )
 {
 
    
      int
    
       a;
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      a);
 
    
      if
    
       (a 
    
      ==
    
       
    
      1
    
      )
 map[i][j] 
    
      =
    
       
    
      false
    
      ;
 
    
      else
    
      
 map[i][j] 
    
      =
    
       
    
      true
    
      ;
 
    
      if
    
       (a 
    
      ==
    
       
    
      2
    
      )
 {
 s.x 
    
      =
    
       i;
 s.y 
    
      =
    
       j;
 }
 
    
      if
    
       (a 
    
      ==
    
       
    
      3
    
      )
 {
 e.x 
    
      =
    
       i;
 e.y 
    
      =
    
       j;
 }
 }
}


    
      int
    
       fail(Point 
    
      &
    
      a)
{
 
    
      if
    
       (a.x 
    
      <
    
       
    
      0
    
       
    
      ||
    
       a.y 
    
      <
    
       
    
      0
    
       
    
      ||
    
       a.x 
    
      >=
    
       n 
    
      ||
    
       a.y 
    
      >=
    
       m)
 
    
      return
    
       
    
      -
    
      1
    
      ;
 
    
      if
    
       (
    
      !
    
      map[a.x][a.y])
 
    
      return
    
       
    
      1
    
      ;
 
    
      return
    
       
    
      0
    
      ;
}


    
      void
    
       dfs(Point 
    
      &
    
      a, 
    
      int
    
       step)
{
 
    
      if
    
       (step 
    
      >=
    
       
    
      10
    
      )
 
    
      return
    
      ;
 Point b;
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       
    
      4
    
      ; i
    
      ++
    
      )
 {
 b.x 
    
      =
    
       a.x 
    
      +
    
       dir[i][
    
      0
    
      ];
 b.y 
    
      =
    
       a.y 
    
      +
    
       dir[i][
    
      1
    
      ];
 
    
      if
    
       (fail(b))
 
    
      continue
    
      ;
 
    
      int
    
       x;
 
    
      while
    
       (
    
      !
    
      (x 
    
      =
    
       fail(b)))
 {
 
    
      if
    
       (b.x 
    
      ==
    
       e.x 
    
      &&
    
       b.y 
    
      ==
    
       e.y)
 {
 found 
    
      =
    
       
    
      true
    
      ;
 ans 
    
      =
    
       min(ans, step 
    
      +
    
       
    
      1
    
      );
 
    
      return
    
      ;
 }
 b.x 
    
      +=
    
       dir[i][
    
      0
    
      ];
 b.y 
    
      +=
    
       dir[i][
    
      1
    
      ];
 }
 
    
      if
    
       (x 
    
      ==
    
       
    
      -
    
      1
    
      )
 
    
      continue
    
      ;
 map[b.x][b.y] 
    
      =
    
       
    
      true
    
      ;
 b.x 
    
      -=
    
       dir[i][
    
      0
    
      ];
 b.y 
    
      -=
    
       dir[i][
    
      1
    
      ];
 dfs(b, step 
    
      +
    
       
    
      1
    
      );
 b.x 
    
      +=
    
       dir[i][
    
      0
    
      ];
 b.y 
    
      +=
    
       dir[i][
    
      1
    
      ];
 map[b.x][b.y] 
    
      =
    
       
    
      false
    
      ;
 }
}


    
      int
    
       main()
{
 
    
      //
    
      freopen("t.txt", "r", stdin);
    
      

    
       
    
      while
    
       (scanf(
    
      "
    
      %d%d
    
      "
    
      , 
    
      &
    
      m, 
    
      &
    
      n), m 
    
      |
    
       n)
 {
 input();
 found 
    
      =
    
       
    
      false
    
      ;
 ans 
    
      =
    
       
    
      20
    
      ;
 dfs(s, 
    
      0
    
      );
 
    
      if
    
       (found)
 printf(
    
      "
    
      %d\n
    
      "
    
      , ans);
 
    
      else
    
      
 printf(
    
      "
    
      %d\n
    
      "
    
      , 
    
      -
    
      1
    
      );
 }
 
    
      return
    
       
    
      0
    
      ;
}