Coin Toss--POJ 3440

1、解题思路：概率论，计算几何。

2、注意事项：题意理解圆心在m*n的矩形中运动；中间值用double类型记录；注意题干中的输出格式。

3、实现方法：

  
    

   
     
   
     #include
   
     <
   
     iostream
   
     >
   
     
#include
   
     <
   
     math.h
   
     >
   
     

   
     using
   
      
   
     namespace
   
      std;

   
     #define
   
      PI 3.141592653
   
     


   
     int
   
      main()
{
 
   
     int
   
      num,i;
 
   
     double
   
      m,n,t,c;
 
   
     double
   
      pro1,pro2,pro3,pro4;
 cin
   
     >>
   
     num;
 
   
     for
   
     (i
   
     =
   
     1
   
     ;i
   
     <=
   
     num;i
   
     ++
   
     )
 {
 cin
   
     >>
   
     m
   
     >>
   
     n
   
     >>
   
     t
   
     >>
   
     c;
 
   
     double
   
      sq
   
     =
   
     m
   
     *
   
     n
   
     *
   
     t
   
     *
   
     t;
 pro2
   
     =
   
     (m
   
     -
   
     1
   
     )
   
     *
   
     n
   
     *
   
     t
   
     *
   
     c
   
     +
   
     (n
   
     -
   
     1
   
     )
   
     *
   
     m
   
     *
   
     t
   
     *
   
     c
   
     -
   
     2
   
     *
   
     (m
   
     -
   
     1
   
     )
   
     *
   
     (n
   
     -
   
     1
   
     )
   
     *
   
     c
   
     *
   
     c;
 pro2
   
     =
   
     pro2
   
     /
   
     sq;

 pro3
   
     =
   
     (m
   
     -
   
     1
   
     )
   
     *
   
     (n
   
     -
   
     1
   
     )
   
     *
   
     c
   
     *
   
     c
   
     *
   
     (
   
     1
   
     -
   
     PI
   
     /
   
     4
   
     );
 pro3
   
     =
   
     pro3
   
     /
   
     sq;

 pro4
   
     =
   
     (m
   
     -
   
     1
   
     )
   
     *
   
     (n
   
     -
   
     1
   
     )
   
     *
   
     c
   
     *
   
     c
   
     *
   
     PI
   
     /
   
     4
   
     ;
 pro4
   
     =
   
     pro4
   
     /
   
     sq;
 
 pro1
   
     =
   
     1
   
     -
   
     (pro2
   
     +
   
     pro3
   
     +
   
     pro4);

 cout
   
     <<
   
     "
   
     Case 
   
     "
   
     <<
   
     i
   
     <<
   
     "
   
     :
   
     "
   
     <<
   
     endl;
 cout.setf(ios::
   
     fixed
   
     );
 cout.precision(
   
     4
   
     );
 cout
   
     <<
   
     "
   
     Probability of covering 1 tile = 
   
     "
   
     <<
   
     pro1
   
     *
   
     100
   
     <<
   
     "
   
     %
   
     "
   
     <<
   
     endl;
 cout
   
     <<
   
     "
   
     Probability of covering 2 tiles = 
   
     "
   
     <<
   
     pro2
   
     *
   
     100
   
     <<
   
     "
   
     %
   
     "
   
     <<
   
     endl;
 cout
   
     <<
   
     "
   
     Probability of covering 3 tiles = 
   
     "
   
     <<
   
     pro3
   
     *
   
     100
   
     <<
   
     "
   
     %
   
     "
   
     <<
   
     endl;
 cout
   
     <<
   
     "
   
     Probability of covering 4 tiles = 
   
     "
   
     <<
   
     pro4
   
     *
   
     100
   
     <<
   
     "
   
     %
   
     "
   
     <<
   
     endl;

 
   
     if
   
     (i
   
     !=
   
     num)
 cout
   
     <<
   
     endl;
 }
 
   
     return
   
      
   
     0
   
     ;
}