c++第四次作业

一.输出星号图

#include <iostream>   using namespace std;int main( ){int i,n,k,m,g;for(i=1;i<=5;i++)cout<<" ";cout<<"*"<<endl;for(n=1;n<=4;n++){for(k=1;k<=5-n;k++)cout<<" ";cout<<"*";{for(m=1;m<=2*n-1;m++)cout<<" ";cout<<"*"<<endl;}}for(g=1;g<=11;g++)cout<<"*";return 0;}

二.编程序，输出1/3-3/5+5/7-7/9…+19/21的结果（答案：-0.383842）

#include <iostream>   using namespace std;int main( ){double i,k=1,s=0;for(i=2;i<=11;i++){s=s+k*((2*(i-1)-1)/(2*i-1));k=-1*k;}cout<<s<<endl;return 0;}

三.百钱百鸡问题

#include <iostream>   using namespace std;int main( ){int x,y;double z;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){cout<<"鸡翁"<<x<<"只,"<<"鸡母"<<y<<"只，"<<"鸡雏"<<z<<"只。"<<endl;}return 0;}