概率的一些练习

#define Mod 1000000007
class Ants {
public:
    vector<int> collision(int n) 
    {
        int down=pow(2.0,n),up=down-2;
        int temp=gcd(up,down);
        vector<int> res;
        res.push_back(up/temp);
        res.push_back(down/temp);
        return res;
    }
    int gcd(int x,int y)
    {
        return (!y)?x:gcd(y,x%y);
    }
};

class RandomP {
public:
    static int f();
};

class Random01 {
public:
    // 用RandomP::f()实现等概率的01返回
    int random01() 
    {
        int a,b;
        while(1)
        {
            a=RandomP::f();
            b=RandomP::f();
            if(a!=b)
                return (a>b)?0:1;
        }
    }
};

// 以下内容请不要修改
class Random5 {
public:
    static int randomNumber();
};

class Random7 {
public:
    int rand5() {
        return Random5::randomNumber();
    }
    // 以上内容请不要修改


    int randomNumber() 
    {
        int a=5*(rand5()-1)+rand5()-1;
        while(a>20)
            a=5*(rand5()-1)+rand5()-1;
        return a%7+1;
    }  
};

class RandomSeg {
public:
    // 等概率返回[0,1)
    double f() {
        return rand() * 1.0 / RAND_MAX;
    }
    // 通过调用f()来实现
    double random(int k, double x) 
    {
        double res=-1;
        for(int i=0;i<k;i++)
        {
            double b=f();
            res=(res>b)?res:b;
        }
        return res;
    }
};

class RandomPrint {
public:
    vector<int> print(vector<int> arr, int N, int M) 
    {
        vector<int> res;
        for(int i=0;i<M;i++)
        {
            int pos=rand()%(N-i);
            res.push_back(arr[pos]);
            swap(arr[pos],arr[N-i-1]);
        }
        return res;
    }
};

#define Mod 1000000007
class Championship {
public:
    vector<int> calc(int k) 
    {
        vector<int> res;
        int up=1,down=1,i=2*k-1;
        while(i>0)
        {
            down*=i;
            i=i-2;
        }
        i=k+1;
        while(i>2)
        {
            up*=i;
            i--;
        }
        int Com=gcd(down-up,down);
        res.push_back((down-up)/Com);
        res.push_back(down/Com);
        return res;
    }
    int gcd(int x, int y)
    {
        return (!y)?x:gcd(y,x%y);
    }
};