作业：C++作业4

项目2-分数的累加:

#include <iostream>using namespace std;int main (){double sum=0,x=0;int i=1,k=1;while(i<=19){  x=i*1.0/(i+2)*k;  k=-k;   sum+=x;  i=i+2;   }    cout<<"sum="<<sum<<endl;    return 0;}

百钱百鸡问题：

#include<iostream>using namespace std;int main(){int x,y,z;for(x=0;x<=20;x++)      for(y=0;y<=33;y++)  for(z=0;z<=100;z++)if(x+y+z==100&&5*x+3*y+z/3==100)cout<<":鸡翁"<<x<<"只,鸡母"<<y<<"只,鸡雏"<<z<<"只。\n";return 0;}

项目6：输出星号图：

#include<iostream>using namespace std;int main(){int i,j;for(i=1;i<=5;i++){   for(j=0;j<6-i;j++)   cout<<" ";   cout<<"*";       for(j=1;j<=2*i-3;j++)         cout<<" ";   if(i==1)cout<<endl;   if(i>1)cout<<"*"<<endl;}       for(j=1;j<=11;j++)     cout<<"*";       cout<<endl; return 0;}