c++第四次作业

#include <iostream>

using namespace std;

int main()
{
double i=1,a=3,k=1,sum=0;
while (i<=19&&a<=21)
{
sum=sum+i/a*k;
i=i+2;
a=a+2;
k=-k;
}

cout<<"1/3-3/5+5/7-7/9…+19/21的结果为"<<sum<<endl;
return 0;
}

#include <iostream>

using namespace std;

int main()
{
int i,k,n=6;
for(i=1; i<=n-1; i=i+1)
cout<<" ";
cout<<"*"<<endl;
for(i=2;i<=n-1;i=i+1)
{
for(k=1; k<=n-i; k=k+1)
cout<<" ";
cout<<"*";
for(k=1; k<=2*i-3; k=k+1)
cout<<" ";
cout<<"*"<<endl;
}
for(i=1; i<=2*n-1; i=i+1)
cout<<"*";
return 0;
}

<span style="font-size:14px;">#include<iostream>
using namespace std;
int main()
{
float x,y,z;
for(x=0;x<=100;x++)
for(y=0;y<=100;y++)
{
z=100-x-y;
if(5*x+3*y+z/3==100) cout<<"鸡翁"<<x<<"只，"<<"鸡母"<<y<<"只，"<<"鸡雏"<<z<<"只"<<endl;
}
return 0;
}</span>

<span style="font-size:18px;">#include<iostream>
using namespace std;
int main()
{
float x,y,z;
for(x=0;x<=3;x++)
for(y=0;y<=3;y++)
{
z=8-x-y;
if(z<=6) cout<<"白球"<<x<<"个，"<<"红球"<<y<<"个，"<<"黑球"<<z<<"个"<<endl;
}
return 0;
}</span>