习题2-1
#include <stdio.h>
int main(){
int sum=1;
for(int i=1;i<=5;i++) sum*=i;
printf("%d\n",sum);
return 0;
}
习题2-3
#include <stdio.h>
int main(){
for(int year=2000;year<2500;year++){
if(year%400==0||(year%4==0&&year%100))
printf("%d年是闰年\n",year);
else printf("%d年不是闰年\n",year);
}
return 0;
}
习题2-4
#include <stdio.h>
int main(){
double ans=0;
for(double i=1;i<=99;i+=2){
ans+=1/i-1/(i+1);
}
printf("%lf\n",ans);
return 0;
}
习题2-5
#include <stdio.h>
#include <math.h>
int main(){
int a,b;
scanf("%d",&a);
b=sqrt(a+0.5);
for(int i=2;i<=b;i++)
if(a%i==0){
printf("不是素数");
return 0;
}
printf("是素数");
return 0;
return 0;
}
附加题1
#include <stdio.h>
int main(){
int ans=0;
for(int i=1;i<=99;i+=2) ans+=i*(i+1);
printf("%d\n",ans);
return 0;
}
附加题2
#include <stdio.h>
int main(){
double ans=0,n=1;
for(double i=1;i<=20;i++){
n*=i;
ans+=1/n;
}
printf("%lf\n",ans);
return 0;
}
附加题3
#include <stdio.h>
#include <math.h>
int main(){
double a,b,c,d;
scanf("%lf%lf%lf",&a,&b,&c);
d=b*b-4*a*c;
if(d<0) printf("无解\n");
else if(d==0) printf("一个解:%lf",-b/(2*a));
else printf("两个不同解:%lf %lf",(-b+d)/(2*a),(-b-d)/(2*d));
return 0;
}