10432 - Polygon Inside A Circle

[p!ter]

Hi sohel
I rebuild my code and got ACC...
Thanx!!!!!!!!
It is not mantioned that radius can be real

[J&Jewel]

My program is ok for sample input output
can anybody give me some I/O...plz..
or any hints..

Code: Select all

#define PI acos(0)
int main()
{
	double r,angle,area;
	int n;
	//freopen("F:\\10432.txt","r",stdin);
	while(scanf("%lf%d",&r,&n)==2)
	{
		angle=180-((double)180*(n-2)/n);
		area=sin(PI/180*angle)*r*r*n/2.0;
		printf("%.3lf\n",2*area);
	}
	return 0;
}

[challenger]

I am always getting Wrong Answer (WA) ! Why is that?
Can anyone find the bug in my code? I would really appreciate that.

Code: Select all

#include <stdio.h>
#include <math.h>

#define pi 2.*acos(0)

main()
{
	float r,n,b,h,ang,area;

	while( scanf("%f %f",&r,&n)==2 )
	{
		ang=(2.*pi)/n;
		b=r*sin(ang);
		h=sqrt(r*r-b*b/4.);
		area=n*(b*h/2.);
		printf("%.3f\n",area);
	}
}

[Darko]

I think you should use doubles. And there is a simple formula for the area.

I don't even think your formula should work - b should be 2.0*r*sin(ang/2.0), draw a picture.

Try

1 4
0.7071 4

you should get
2.000
1.000

Darko

[challenger]

Ok! I fixed the double thing and the base and height formulads

[removed]

Double in ANSII is %f but I had to change it to %lf ... that was my error.

[Darko]

Heh, I'm glad for you, but you shouldn't be posting accepted code, please remove it.

Darko

[gvs]

does anybody know why this occurs ?
I tried my code on both Windows, and Ubuntu, but there was no difference... I used acos(0.0) for pi... and kept getting WA.
But when i used acos(-1.0), i finally got AC...

god knows why ....
this is the 3rd such problem I've faced in the last 5... n it's drivin me crazy...

makes coding much more difficult and infuriating...

[Ankur Jaiswal]

may be the WA's came bcoz u took the value of PI from any other source(may be u have searched google or seen math.h).
In general always use PI=2*acos(0.0). you wont get precision errors then.

[kolpobilashi]

[code]

#include<stdio.h>
#include<math.h>

int main()
{
int r,n;
while(scanf("%d %d",&r,&n)!=EOF)
{
double s,f,PI;
PI=2*acos(0.0);
f=sin(2*PI/(double)n);
s=(double)(.5*r*r*f*n);
printf("%.3lf\n",s);
}
return 0;
}

[/code]

[Moha]

the problem statements dosn't say that 'r' is an integer number . read it as a double and try again.

[kolpobilashi]

thanx a lottt!!!
Acc now

[deena sultana]

Hi, friends, again i need your help.
i got WA for 10432. but i dont understand why.
would you plz help me?

Code: Select all

Removed After AC;

[emotional blind]

Unfortunately your formula is Wrong
If u use sin instead of asine it should be right


If you get ACCEPTED
Dont be lazy to remove your code please
otherwise it spoils the problem

Best wishes

[emotional blind]

Unfortunately your formula is Wrong
If u use sin instead of asine it should be right


If you get ACCEPTED
Dont be lazy to remove your code please
otherwise it spoils the problem

Best wishes

[deena sultana]

emotional blind

u r sooooooooo nice.
Thank u very much.
i get ac now.