C++作业4

#include <iostream>
using namespace std;
void main ()
{
int i=1,k=1;
double sum=0;
while  (i<=19)
{
sum=((double)i/(i+2))*k+sum;

i=i+2;

k=-k;
}

cout<<"sum="<<sum<<endl;

}

#include <iostream>
using namespace std;
void main()
{
int i,j,k;
cout<<"    "<<"*"<<endl;
for (i=2;i<=5;i++)
{
for(j=0;j<5-i;j++)

cout<<" ";
cout<<"*";

for(k=1;k<=2*(i-1);k++)

cout<<" ";
cout<<"*"<<endl;
}
cout<<"************"<<endl;

}

#include <iostream>
using namespace std;
void main ()
{
int x,y,z ,count=0;
cout<<"买鸡的方案有"<<endl;
for(x=0;x<=20;x++)
for(y=0;y<=33;y++)
for(z=0;z<=300;z++)
if(5*x+3*y+z/3==100&&x+y+z==100)
{
++count;
cout<<"方案"<<count<<":"<<x<<"只公鸡"<<y<<"只母鸡"<<z<<"只鸡雏"<<endl;
}

}