poj 3440 Coin Toss 概率问题

这题主要是推导数学公式！！！

将概率问题转化为圆心所在的面积！

代码如下：

 

#include<iostream>

#include<stdio.h>

#include<algorithm>

#include<iomanip>

#include<cmath>

#include<cstring>

#define pi acos(-1.0)

using namespace std;

int main()

{

    int i=0,k;

    double a1,a2,a3,a4,sum,r,m,n,t,c;

    cin>>k;

    while(k--){

        cin>>m>>n>>t>>c;

        r=c/2.0;

        sum=m*n*t*t;

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

        a3=(c*c-pi*r*r)*(m-1)*(n-1);

        a4=pi*r*r*(m-1)*(n-1);

        a1=sum-a2-a3-a4;

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

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

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

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

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

        printf("\n");

    }

}

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