Solution Tricks Of Light Online Judge - 1433 - Minimum Arc Distance

Problem Statement :

You all probably know how to calculate the distance between two points in two dimensional cartesian plane. But in this problem you have to find the minimum arc distance between two points and they are on a circle centered at another point.

You will be given the co-ordinates of the points A and B and co-ordinate of the center O. You just have to calculate the minimum arc distance between A and B. In the picture, you have to calculate the length of arc ACB. You can assume that A and B will always be on the circle centered at O.

Solution Code :

#include<cmath>
#include<cstdio>
#include<iostream>
using namespace std;

int main()
{
    int i,test;
    int Ox,Oy,Ax,Ay,Bx,By;
    double AB,OB,result,alpha;
    cin>>test;
    for(i=1;i<=test;i++)
    {
        cin>>Ox>>Oy>>Ax>>Ay>>Bx>>By;
        AB = (Ax-Bx)*(Ax-Bx)+(Ay-By)*(Ay-By);
        AB = sqrt(AB);

        OB = (Ox-Bx)*(Ox-Bx)+(Oy-By)*(Oy-By);
        OB = sqrt(OB);

        result = 2*OB*OB - AB*AB;
        result = result/(2*OB*OB);

        alpha = acos (result ) ;
        result = alpha * OB ;
        printf("Case %d: %lf\n",i,result);
    }
    return 0;
}