C++作业4



项目一：输出1/3-3/5+5/7-7/9…+19/21的结果：

#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;
	
}

项目二：输出星号图 ：

#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;  
	
} 

项目三：百钱百鸡问题：

#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;
			   }

}