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。。。。。

//3440
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <math.h>
#define PI acos(-1.0)

using namespace std ;

int main()
{
    int k;
    double a1,a2,a3,a4,sum;
    double c,m,n,t;
    scanf("%d",&k) ;
    for(int i = 1 ; i <= k ; i++){
       scanf("%lf %lf %lf %lf",&m,&n,&t,&c) ;
        sum = m*n*t*t;
        a1 = (t-c)*(t-c)*n*m+(c*(t-c)+c*c/4.0)*4+c*(t-c)*(n+m-4) ;
        a2 = (m-1)*n*t*c+(n-1)*m*t*c-2*(m-1)*(n-1)*c*c;
        a3 = (m-1)*(n-1)*c*c*(1-PI/4);
        a4 = (m-1)*(n-1)*c*c*PI/4;
        printf("Case %d:
",i);
        printf("Probability of covering 1 tile  = %.4f%%
",100*a1/sum);
        printf("Probability of covering 2 tiles = %.4f%%
",100*a2/sum);
        printf("Probability of covering 3 tiles = %.4f%%
",100*a3/sum);
        printf("Probability of covering 4 tiles = %.4f%%
",100*a4/sum);
        printf("
");
    }
    return 0 ;
}