POJ 3440 Coin Toss（求概率）

题目链接

题意 ：把硬币往棋盘上扔，分别求出硬币占1，2，3，4个格子的时候的概率。

思路 ： 求出公式输出，不过要注意输出格式，我还因为输入的时候用了int类型错了好几次。。。。。

 1 //3440

 2 #include <stdio.h>

 3 #include <string.h>

 4 #include <iostream>

 5 #include <math.h>

 6 #define PI acos(-1.0)

 7 

 8 using namespace std ;

 9 

10 int main()

11 {

12     int k;

13     double a1,a2,a3,a4,sum;

14     double c,m,n,t;

15     scanf("%d",&k) ;

16     for(int i = 1 ; i <= k ; i++){

17        scanf("%lf %lf %lf %lf",&m,&n,&t,&c) ;

18         sum = m*n*t*t;

19         a1 = (t-c)*(t-c)*n*m+(c*(t-c)+c*c/4.0)*4+c*(t-c)*(n+m-4) ;

20         a2 = (m-1)*n*t*c+(n-1)*m*t*c-2*(m-1)*(n-1)*c*c;

21         a3 = (m-1)*(n-1)*c*c*(1-PI/4);

22         a4 = (m-1)*(n-1)*c*c*PI/4;

23         printf("Case %d:\n",i);

24         printf("Probability of covering 1 tile  = %.4f%%\n",100*a1/sum);

25         printf("Probability of covering 2 tiles = %.4f%%\n",100*a2/sum);

26         printf("Probability of covering 3 tiles = %.4f%%\n",100*a3/sum);

27         printf("Probability of covering 4 tiles = %.4f%%\n",100*a4/sum);

28         printf("\n");

29     }

30     return 0 ;

31 }

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