c++作业4

#include <iostream.h>
void main()
{
int i=1,k=1;
double sum=0;
while(i<=10)
{
sum=sum+double(k)*(2*i-1)/(2*(i+1)-1);
i++;
k=-k;
}
cout<<"1/3-3/5+5/7-7/9…+19/21的结果为"<<sum<<endl;
}

#include <iostream.h>
void main()
{
int i,j,k;
cout<<"不同的颜色搭配方法有："<<endl;
for(i=0;i<=3;i++)
for(j=0;j<=3;j++)
for(k=1;k<=6;k++)
if(i+j+k==8)
cout<<"白球: "<<i<<"红球:"<<j<<"黑球："<<k<<endl;
}

#include <iostream>
using namespace std;
int main()
{
int i,a=100000,sum1=0;
double b=0.01,sum2=0;
for(i=1;i<=30;i++)
{
sum2=sum2+b;
cout<<"第"<<i<<"天富翁给陌生人的钱："<<b<<endl;
cout<<"第"<<i<<"天陌生人给富翁的钱："<<a<<endl;
b=b*2;
}
sum1=a*30;
cout<<"30天后陌生人给了百万富翁"<<sum1<<"元"<<endl;
cout<<"30天后百万富翁给了陌生人"<<sum2<<"元"<<endl;
if(sum1>sum2)  cout<<"富翁赚了！";
else if(sum1<sum2)  cout<<"富翁亏了！";
else cout<<"富翁不赚不亏！";
return 0;
}