hdu2080-2081

hdu2080

计算两点关于原点夹角，数学

 #include<stdio.h>
 #include<math.h>
 double len(double x1,double y1,double x2,double y2){
     return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
 }
 int main(){
     int T;
     while(scanf("%d",&T)!=EOF){
         for(int q=;q<=T;q++){
             double x1,y1,x2,y2;
             double a,b,c;
             scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
             a=len(,,x1,y1);
             b=len(,,x2,y2);
             c=len(x1,y1,x2,y2);
             double cos1=(a*a+b*b-c*c)/(*a*b);
             double t=acos(cos1)*/3.14159;
             printf("%.2lf\n",t);
         }
     }
     return ;
 }

hdu2081

模拟

 #include<stdio.h>

 int main(){
     int N;
     while(scanf("%d",&N)!=EOF){
         for(int q=;q<=N;q++){
             char a[];
             scanf("%s",a);
             printf("");
             for(int i=;i<=;i++)printf("%c",a[i]);
             printf("\n");
             getchar();
         }
     }
     return ;
 }