Sudoku--POJ 2676

1、解题思路：经典深度搜索。

2、注意事项：输入单个字符scanf、cin.get()；DFS中搜索比较位置的判断；正搜超时，反搜0ms。

3、实现方法

  
    

   
     
   
     #include
   
     <
   
     iostream
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;


   
     struct
   
      Node
{
 
   
     int
   
      num;
 
   
     bool
   
      change;
};


   
     struct
   
      Pos
{
 
   
     int
   
      x,y;
};


   
     int
   
      begin[
   
     4
   
     ]
   
     =
   
     {
   
     0
   
     ,
   
     1
   
     ,
   
     4
   
     ,
   
     7
   
     };

   
     int
   
      end[
   
     4
   
     ]
   
     =
   
     {
   
     0
   
     ,
   
     3
   
     ,
   
     6
   
     ,
   
     9
   
     };

Node map[
   
     10
   
     ][
   
     10
   
     ];
Pos Arr[
   
     100
   
     ];

   
     int
   
      cnt,mark;


   
     void
   
      Init()
{
 
   
     char
   
      ch;
 mark
   
     =
   
     0
   
     ;
 cnt
   
     =
   
     0
   
     ;
 
   
     for
   
     (
   
     int
   
      i
   
     =
   
     1
   
     ;i
   
     <=
   
     9
   
     ;i
   
     ++
   
     )
 {
 
   
     for
   
     (
   
     int
   
      j
   
     =
   
     1
   
     ;j
   
     <=
   
     9
   
     ;j
   
     ++
   
     )
 {
 scanf(
   
     "
   
     %c
   
     "
   
     ,
   
     &
   
     ch);
 map[i][j].num
   
     =
   
     int
   
     (ch
   
     -
   
     '
   
     0
   
     '
   
     ); 
 
   
     if
   
     (map[i][j].num
   
     ==
   
     0
   
     )
 {
 map[i][j].change
   
     =
   
     true
   
     ;
 cnt
   
     ++
   
     ;
 Arr[cnt].x
   
     =
   
     i;
 Arr[cnt].y
   
     =
   
     j;
 }
 
   
     else
   
     
 map[i][j].change
   
     =
   
     false
   
     ;
 }
 cin.
   
     get
   
     (ch);
 }
}


   
     bool
   
      Judge(
   
     int
   
      step,
   
     int
   
      num)
{
 
   
     int
   
      x
   
     =
   
     Arr[step].x;
 
   
     int
   
      y
   
     =
   
     Arr[step].y; 
 
   
     for
   
     (
   
     int
   
      i
   
     =
   
     1
   
     ;i
   
     <=
   
     9
   
     ;i
   
     ++
   
     )
 {
 
   
     if
   
     (i
   
     ==
   
     y
   
     ||
   
     map[x][i].num
   
     !=
   
     num)
 
   
     continue
   
     ;
 
   
     else
   
     
 
   
     return
   
      
   
     false
   
     ;
 } 
 
   
     for
   
     (
   
     int
   
      j
   
     =
   
     1
   
     ;j
   
     <=
   
     9
   
     ;j
   
     ++
   
     )
 {
 
   
     if
   
     (j
   
     ==
   
     x
   
     ||
   
     map[j][y].num
   
     !=
   
     num)
 
   
     continue
   
     ;
 
   
     else
   
     
 
   
     return
   
      
   
     false
   
     ;
 } 
 
   
     int
   
      tmp_x
   
     =
   
     x
   
     /
   
     3
   
     ;
 
   
     if
   
     (x
   
     %
   
     3
   
     !=
   
     0
   
     )
 tmp_x
   
     ++
   
     ; 
 
   
     int
   
      tmp_y
   
     =
   
     y
   
     /
   
     3
   
     ;
 
   
     if
   
     (y
   
     %
   
     3
   
     !=
   
     0
   
     )
 tmp_y
   
     ++
   
     ; 
 
   
     for
   
     (
   
     int
   
      p
   
     =
   
     begin[tmp_x];p
   
     <=
   
     end[tmp_x];p
   
     ++
   
     )
 {
 
   
     for
   
     (
   
     int
   
      q
   
     =
   
     begin[tmp_y];q
   
     <=
   
     end[tmp_y];q
   
     ++
   
     )
 {
 
   
     if
   
     ((p
   
     ==
   
     x
   
     &&
   
     q
   
     ==
   
     y)
   
     ||
   
     map[p][q].num
   
     !=
   
     num)
 
   
     continue
   
     ;
 
   
     else
   
     
 
   
     return
   
      
   
     false
   
     ;
 }
 } 
 
   
     return
   
      
   
     true
   
     ; 
}


   
     void
   
      DFS(
   
     int
   
      step)
{ 
 
   
     if
   
     (step
   
     ==
   
     1
   
     )
 {
 mark
   
     =
   
     1
   
     ; 
 
   
     for
   
     (
   
     int
   
      j
   
     =
   
     1
   
     ;j
   
     <=
   
     9
   
     ;j
   
     ++
   
     )
 {
 
   
     if
   
     (Judge(step,j))
 {
 map[Arr[step].x][Arr[step].y].num
   
     =
   
     j;
 DFS(step
   
     -
   
     1
   
     );
 
   
     if
   
     (
   
     !
   
     mark)
 map[Arr[step].x][Arr[step].y].num
   
     =
   
     0
   
     ;
 }
 }
 }
 
   
     if
   
     (
   
     !
   
     mark)
 { 
 
   
     for
   
     (
   
     int
   
      i
   
     =
   
     1
   
     ;i
   
     <=
   
     9
   
     ;i
   
     ++
   
     )
 {
 
   
     if
   
     (Judge(step,i))
 {
 map[Arr[step].x][Arr[step].y].num
   
     =
   
     i;
 DFS(step
   
     -
   
     1
   
     );
 
   
     if
   
     (
   
     !
   
     mark)
 map[Arr[step].x][Arr[step].y].num
   
     =
   
     0
   
     ;
 }
 }
 } 
}


   
     int
   
      main()
{
 
   
     int
   
      n;
 
   
     char
   
      s;
 cin
   
     >>
   
     n;
 cin.
   
     get
   
     (s);
 
   
     while
   
     (n
   
     --
   
     )
 {
 Init();
 DFS(cnt); 
 
   
     if
   
     (mark)
 {
 
   
     for
   
     (
   
     int
   
      i
   
     =
   
     1
   
     ;i
   
     <=
   
     9
   
     ;i
   
     ++
   
     )
 {
 
   
     for
   
     (
   
     int
   
      j
   
     =
   
     1
   
     ;j
   
     <=
   
     9
   
     ;j
   
     ++
   
     )
 cout
   
     <<
   
     map[i][j].num;
 cout
   
     <<
   
     endl;
 }
 }
 }
 
   
     return
   
      
   
     0
   
     ;
}